VKI Seminar Series

VKI Seminars Series

Free registration in respect with the VKI eligibility criteria. You will receive the information to join the seminar of your choice after the registration.

Sailboat hydrodynamics and challenges (on-site for VKI staff / online - Open to public)

Benoît Mallol from Cadence

Abstract:The top designers for the America's Cup, the Vendée Globe, and other international racing regattas, need to predict the performances of the sailing boats for many wind and sea conditions, and CFD (Computational Fluid Dynamics) methods are used in this context to multiply the number of tests and even replace towing tanks or cavitation tunnels. In fact, CFD is no longer an option, it is vital for all these teams to master their designs and be ahead of the competition. Accuracy, speed, and automation are the keys of a successful CFD workflow that this seminar will explore around the sailing boat industry, towards extensive matrix calculations on HPC clusters. This seminar explains in detail the challenges and the different CFD features required for sailing boat design and will be interesting for marine engineers and naval architects working in the sailing yacht industry.

Short biography: Benoit Mallol holds a master's degree in Mechanical and Numerical modeling from the University of Bordeaux (France) with a specialization in CFD dedicated to free surface flows. For more than 15 years, he has been working on unstructured meshing strategies and marine applications. As head of the marine group and head of the unstructured meshing applications group, Benoit drives the product roadmaps and acts as the CFD technical expert to support all customer projects around the world from the marine industry.

Design aspects and features of isotherm gas compressors delivered (on-site / online - Restricted to VKI Staff and Students)

Dr. Luca Porreca, Product Manager at MAN Energy Solutions AG

Abstract: It is well known that gas compressor work can be greatly reduced by inter-stage cooling. Since decades, isotherm compressors are commonly used where very large volume of gases is needed and low power consumption is necessary, so that the efficiency of the industrial process is greatly improved. Depending on the discharge pressure and the energy evaluation, isotherm compressors can be designed with 2 to 5 intercoolers and 3 to 10 centrifugal stages, thus adapting the compressor to deliver gas at a pressure ratio ranging between 4.5 and 20 in a single, compact casing. Nowadays in the market offers mainly 2 different types of isotherm compressors: Inline compressors (integrated isotherm type, as shown in Figure 1a) and geared-type compressors (with external coolers, shown in Figure 1b). In both cases, the intercooling process has a great impact on the compression efficiency, but it is often challenging to optimize performances vs. reliability and evaluate costs vs. benefits. The main applications of isothermal compressors are air separation industries (ASU plants), iron and steel factories, fertilizer industry, Enhanced Oil Recovery (EOR) plant, Compressed Air Energy Storage (CAES) and CO2 compression. The compressor frame sizes are based on geometrical scaling of most components, leading to a high degree of standardization and reliable performance. If necessary, major components such as impellers and diffusors may be tailored to fit process requirements.
The key optimization goals in this compressor technology are focused either on rotating components (stage aerodynamics, stage matching) as well as on intercooling process. In particular, current development is aiming either on improvement of cooling efficiency or (keeping the same efficiency) on size reduction, which is directly related also to overall cost reduction. The seminar will go through different design details of single shaft and gear-type isotherm compressors. In particular, aerodynamic stage design and limits, stage matching and overall thermodynamic performance optimization including trade-off between compressor costs and performances.

Short biography: Dr. Ing. Luca Porreca has covered different functions at MAN Energy Solution Schweiz AG since 2007 as aerodynamic Project engineer, Project manager and Head of Thermo Group at the Industrial Gases department. He is currently Product Manager for ASU Business (Air Separation Units). He is responsible for technology development of large LP single-shaft isotherm air compressors. He has graduated in mechanical engineering from the university “Roma Tre” in 2001, has attended with honors the VKI Diploma Course in 2002 and holds a PhD from the Swiss Federal Institute of Technology Zürich (ETHZ) since 2007. He is also the chair of the Turbomachinery Committee at the ASME IGTI Turbo Expo in 2022 and 2023.

The aerodynamics of curled wind turbine wakes (on-site for VKI staff / online - open to public)

dr. Luis Tony Martínez-Tossas, National Renewable Energy Laboratory, USA

Short biography: dr. Luis Tony Martínez-Tossas is a research engineer at the National Renewable Energy Laboratory in the United States, with a background in theoretical aerodynamics and numerical simulations for wind energy applications. Tony obtained a Master of Science in Mechanical Engineering from University of Puerto Rico Mayaguez, followed by a PhD in Mechanical Engineering from Johns Hopkins University.

Combustion experiments with large test facilities at ONERA Palaiseau Center (online - open to public)

dr. Axel Vincent-Randonnier, ONERA, France

Abstract: Air breathing propulsion can be achieved with a great variety of engines, from turbomachinery to ram- or scramjet, depending on the speed to be reached. Ground investigation of the combustion processes occurring in true engines then requires testing at the same conditions of pressure, air mass flow and temperature inlet, as flame topology highly depends on kinetics, turbulence level or residence time in the combustor.
For that purpose, large scale test facilities have been developed at ONERA, allowing a great variety of diagnostics. The current presentation will address the following topics:

  • Principle of operation of the large test facilities
  • Mass flow measurement with choked nozzles

For turbomachinery at M1, MICADO and LAERTE-EPICTETE facilities

  • Characterization of engines operability (ignition and lean extinction)
  • Measurement of gaseous and particulate emissions
  • High speed diagnostics (spray and flame)
  • PLIF / LII diagnostics
  • Effusion cooling

For high speed propulsion with LAPCAT-II and STRATOFLY Dual Mode Ramjet combustors:

  • Effect of the equivalence ratio and air temperature on combustion modes.
  • kHz Schlieren and OH* chemiluminescence imaging for the characterization of unsteady combustion.
  • Plasma assisted supersonic combustion

Short biography: dr. Axel Vincent-Randonnier got a PhD on plasma processing for NOx removal from car exhausts at Paris 6 University in 2002. In 2004, he joined ONERA at energetics department in Palaiseau Center to work on experimental plasma-assisted combustion. Two years later, he started research activities on large test rigs, leading experiments on supersonic combustion at LAERTE facility, first with the PREPHA combustor and since 2010 with the LAPCAT2 combustor. Between 2007 and 2019, he also led experiments on subsonic combustion with a second test rig at LAERTE facility (A3C, MICAEDI, EPICTETE combustors). From 2012 to 2019, he managed the MICADO project to develop of a new test facility to investigate high pressure and high temperature air-breathing combustion in turbomachinery. Since 2019, he leads experiments at MICADO test rig. He also led combustion or ignition tests at M1 facility with single or multi-sector industrial combustors between 2017 and 2019. In 2022, he will start experimental investigations on hydrogen/air combustion applied to turbomachinery at MICADO test rig.

Fundamentals of Automotive Aerodynamics and Experimental Applications (online - open to public)

Dr. Emir Öngüner, Application and Sales Representative at Dantec Dynamics

Abstract: As a result of increasing demand of energy efficiency in ground transportation, the aerodynamic aspects gain priority with respect to previous decades. Important attributes as greenhouse gas emissions, limited oil resources and recent competitive electric cars with rechargeable batteries keep the energy and fuel consumption stıll in focus. The drag, crosswind stability, cooling of propulsion and transmission, lift distribution, wind noise and surface soiling… etc. are some significant aerodynamic features which directly interact with the exterior design elements of ground vehicles. Within this seminar it is aimed at giving a general overview on the historical development and practical applications of aerodynamics on ground vehicles.

Short biography: Dr. Öngüner received his diploma in Mechanical Engineering at University of Stuttgart in 2012, Research Master degree at VKI in 2013 and his doctoral degree in Experimental Fluid Mechanics at Brandenburg University of Technology in 2017. He worked several years as research scientist at German Aerospace Center (DLR) – Institute of Aerodynamics and Flow Technology, Göttingen. Currently he is working as application and sales representative at Dantec Dynamics and in charge of supervising the customers in West-Germany and Netherlands.

Quantum turbulence: Why fluid dynamicists should care (online - open to public)

Dr. Katepalli R. Sreenivasan, Professor at New York University

Abstract: This talk provides a perspective on quantum turbulence: what it is, how the subject developed, some key concepts, and its possible relevance to classical fluid dynamics.

Short biography: Dr. Sreenivasan is a University Professor at New York U, where he holds professorships in Department of Physics, Courant Institute of Mathematical Sciences, and Department of Mechanical and Aerospace Engineering. Earlier, he was Dean of the NYU Tandon School of Engineering and President of former Brooklyn Polytechnic, Director of the International Centre for Theoretical Physics in Trieste, and held faculty appointments at U. Maryland, and Yale U. He has been a visiting professor at Caltech, Rockefeller University, Cambridge U., and the Institute for Advanced Study at Princeton. He has been elected to Indian Academy of Sciences, Indian National Science Academy, Academy of Sciences for the Developing World (TWAS), African Academy of Sciences, U.S. National Academy of Sciences, U.S. National Academy of Engineering, American Academy of Arts and Sciences, and Accademia dei Lincei in Rome, etc. His honors include Guggenheim Fellowship; Otto Laporte Award, Fluid Dynamics Prize and Leo Kadanoff Prize all from American Physical Society (APS); von Karman Medal of American Society of Civil Engineers; G.I. Taylor Medal of Society of Engineering Science; Charles Russ Richards Award of American Society of Mechanical Engineers; Indian Institute of Science Distinguished Alumnus Award and Centennial Professorship; Indian Academy of Sciences Sir C.V. Raman Visiting Professorship; International Prize and Gold Medal in memory of Professors Modesto Panetti and Carlo Ferrari; the Nusselt-Reynolds Prize from the Assembly of World Conference on Experimental Heat Transfer, Fluid Mechanics and Thermodynamics; Duty Society and Indian Society of Applied and Industrial Mathematics President Dr. Zakir Husain Memorial Award. In recognition of his work on international science, he has received the National Order of Scientific Merit from the Brazilian Government and Academy of Sciences; UNESCO Medal for Promoting International Scientific Cooperation and World Peace; APS Dwight Nicholson Medal; AAAS Award for International Scientific Cooperation, etc.

Optical emission spectroscopy for thermal protection material response analysis in the VKI Plasmatron facility (online - open to public)

Dr. Bernd Helber, Research Engineer at the von Karman Institute for Fluid Dynamics

Abstract: Dr. Bernd Helber will present some work that has already been shown some while back at the AIAA AVIATION invited special session on Optical Diagnostics in Plasma Facilities

Short biography: Following his Aerospace studies at the University of Stuttgart, Dr. Helber started the Diploma Course at VKI (renamed Research Master) in 2009 and stayed at VKI for his PhD studies, which he finalized affiliated with VUB in 2016 and is working since as research engineer at VKI.

Hybrid Performance assessment of Sand Mitigation Measures (online - open to public)

Dr. Lorenzo Raffaele is Assistant Professor at Politecnico di Torino and Visiting Professor at von Karman Institute for Fluid Dynamics

Abstract: Windblown sand hazard affects building environment, human activities, and ecological system in sandy coastal and desert environments. On the one hand, ongoing climatic changes have increased the frequency and magnitude of windstorms along coastal regions in extra tropical regions, Europe included. On the other hand, desert regions are increasingly hosting human activities and built structures. In light of this, windblown sand interacts with ground-mounted obstacles of any kind inducing sand erosion and sedimentation around them and detrimental effects, such as transport infrastructure loss of capacity, but also destructive failures, such as train derailment. Several Sand Mitigation Measures design solutions to mitigate windblown sand effects have been proposed so far. However, with some remarkable exceptions, their rigorous design and performance assessment remain at their early stage in the engineering literature, while they are mostly based on trial-and-error approaches in the technical practice. This is due to the multidisciplinary and multiphysics/multiscale nature of the phenomenon coupling fluid dynamics and aeolian processes. As a result, on one hand, research should benefit from disciplines adjacent and partially overlapping, e.g. fluid dynamics, wind engineering and aeolian geomorphology. On the other hand, experimental and numerical approaches should be mutually supporting to model multiphase windblown sand processes. In this talk, windblown sand transport is introduced from a phenomenological and modelling point of view. State-of-the-art sand mitigation measures are presented and categorized with respect to their aerodynamic working principle. Then, a hybrid methodology to assess the performance of Sand Mitigation Measures is presented. Such a methodology takes advantaged of both Wind-Sand Tunnel tests and innovative multiphase Computational Fluid Dynamics simulations. Their complementary combination allows to overcome their standalone limitations and to lower the costs with respect to in-situ full scale testing. Finally, a probabilistic approach to assess windblown sand action and plan sand removal maintenance operations is applied. This allows accounting for multiple uncertainties in environmental in-field conditions and for their propagation to the resulting windblown sand action. Such a hybrid methodology constitutes a promising approach to design innovative Sand Mitigation Measures and partially replace and/or assist expensive field tests, usually incompatible with infrastructure designer/stakeholders time requirements.

Short bio: Lorenzo Raffaele is Assistant Professor at Politecnico di Torino and Visiting Professor at von Karman Institute for Fluid Dynamics. The study has been developed in the framework of the MSCA-IF-2019 research project Hybrid Performance Assessment of Sand Mitigation Measures (HyPer SMM, https://hypersmm.vki.ac.be/). This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 885985.

Modelling energy deposition in femtosecond lasers (online - open to public)

Dr. Federico Bariselli, Post Doc, Politecnico di Milano and von Karman Institute

Federico completed his PhD at VKI / VUB / POLITECNICO DI MILANO on DSMC simulations of meteoroid entry in early 2020 and is pursuing his post-doc since with the Politecnico di Milano (in residence at VKI).
Dr. Federico Bariselli will present his current post-doc work on: Modelling energy deposition in femtosecond lasers

Cost function for low-dimensional manifold topology optimization (online - open to public)

Mrs. Kamila Zdybał is a PhD student at Université Libre de Bruxelles, Belgium

Abstract: In the era of big data, numerous science and engineering disciplines use dimensionality reduction to obtain reduced representations of complex physical systems with many degrees of freedom. Large data coming from system measurement or simulation are frequently the starting point of reduced-order modeling. These high-dimensional datasets, ubiquitous to fields such as plasma flows, chemically reacting flows, electrochemistry or atmospheric physics, often exhibit strongly attracting low-rank manifolds. This observation brings hope that describing the system evolution on those manifolds alone can be a viable modeling strategy. After projecting the original variables onto a lower-dimensional basis, complex dynamics can be tracked on a lower-dimensional manifold, embedded in the full-dimensional state space. This approach allows for substantial model reduction, but the quality of the manifold topology becomes a decisive aspect in successful modeling. In this seminar talk, we demonstrate a quantitative metric for characterizing manifold topologies and delineate its few interesting applications to mitigate manifold challenges. Using the metric as a cost function in optimization algorithms, optimal low-dimensional projections can be found. Quality of these projections can be ranked for various linear and nonlinear dimensionality reduction techniques. We show applications of the cost function to datasets in reacting flows, plasma flows and atmospheric physics and demonstrate how it can assess different data preprocessing and dimensionality reduction strategies in their capacity to yield well-defined manifolds. The desired effects include reducing non-uniqueness and spatial gradients in the dependent variable space.

Short biography: Kamila Zdybał is a PhD student at Université Libre de Bruxelles supervised by Professor Alessandro Parente. Her research work is in reduced-order modeling of turbulent reactive flows with applications to combustion. The recent work in improving quality of low-dimensional data projections for efficient model reduction is carried out in collaboration with Professor James C. Sutherland from the University of Utah. As part of her work, Kamila is also developing PCAfold, a Python software package for generating, analyzing and improving low-dimensional manifolds, that can have broad applications in other disciplines outside of combustion.

Hydrogen as a clean energy carrier for the future: challenges and opportunities for high temperature thermal energy conversion (online - open to public)

Univ.-Prof. Dr.-Ing. Heinz Pitsch from the Institut für Technische Verbrennung at RWTH Aachen University, Germany

Prof. Heinz Pitsch form RWTH Aachen has been awarded the Chaire Jaumotte by the Academy of Belgium: https://www.academieroyale.be/fr/who-who-detail/relations/heinz-pitsch/

Thermochemical non-equilibrium effects in hypersonic turbulent boundary layers (online seminar - open to public)

Dr. Donatella Passiatore, Politecnico di Bari and Ecole Nationale Superieure d’Arts et Metiers

Abstract: High-speed turbulent flows are encountered in multiple hypersonic applications in the defense and military fields, as well as in the areas of spatial tourism and trans-atmospheric flight. In such flows, the enhancement of compressibility effects due to the increasing Mach number significantly affects the physical behavior of the gas. Additionally, high-temperature effects arising in hypersonic flights have a major impact on aerodynamic performance of a vehicle. The accurate prediction of the two-way coupling of wall-bounded compressible turbulence and thermochemical processes triggered by the high temperature at stake is a subject partially unexplored. In this talk, the behavior of spatially evolving flat-plate boundary layers in hypersonic conditions is inspected by means of Direct Numerical Simulations (DNS), ensuring no uncertainties deriving from deficiencies of turbulence closure models. Adiabatic and wall-cooled configurations are investigated, from the laminar up to the fully turbulent regime. A five-species air mixture model is considered, with the final aim of studying the effect of finite-rate chemistry and vibrational relaxation on highly compressible turbulent flows. It is found that chemical activity drains energy from the flow and has an impact on transport properties, thermal fields and turbulent fluctuations. Globally, classical correlations of turbulent quantities are found to be in accordance with the results obtained for hypersonic flows under cryogenic conditions. On the other hand, turbulence dynamics and thermal nonequilibrium are tightly coupled. Velocity fluctuations have indeed a major role in the mixing of hot and cold gases, which leads to the excitation of all energetic modes and lags in the vibrational energy with respect to its equilibrium value. Inspections on turbulence/thermochemistry interaction terms have reveled a non-negligible coupling and suggest that particular attention must be paid to the development of turbulence models in the context of hypersonic flows.

Short bio: Donatella recently finished her PhD thesis on “Direct Numerical Simulations of hypersonic turbulent boundary layers with thermochemical non-equilibrium effects” at Politecnico di Bari and Ecole Nationale Superieure d’Arts et Metiers.

How philosophy could help fluid dynamics research?(online seminar - open to public)

Prof. Olivier Chazot, von Karman Institute

Short bio: Prof. Olivier Chazot is Head of the Aeronautics and Aerospace Department at VKI

Particle Methods for the Simulation of Fluid Flow 

Professor Angelo Tafuni from the New Jersey Institute of Technology

The presentation covers a brief introduction of particle methods and their role in CFD, followed by a focused section on Smoothed Particle Hydrodynamics (SPH) and its use in the solution of challenging engineering flows. SPH represents a powerful numerical method when simulating flow with large gradients and/or with one or more interfaces. Prof. Tafuni will introduce the DualSPHysics project (dual.sphysics.org), a massively parallel, open-source code that is developed by a consortium of five universities, including NJIT. He will also talk about projects that involve the use of SPH in his research lab, including new models for studying turbulence in a Lagrangian setting and multiphase flow.

Prof. Tafuni received a "Laurea Triennale" and "Laurea Magistrale" in Mechanical Engineering from Politecnico di Bari, Italy, and a Master of Sciences and PhD from the New York University in Brooklyn, NY. Since 2018, he has been a member of the faculty of the New Jersey Institute of Technology, where he is currently an Assistant Professor in the School of Applied Engineering and Technology and the Department of Mechanical and Industrial Engineering. He is engaged in conducting and supervising research on fluid dynamics and heat transfer theory and applications, with an emphasis on developing and validating new models in Computational Fluid Dynamics. 

Quantum-accelerated scientific computing: concepts, programming tools and applications (online seminar - open to public)

Prof. Matthias Moeller from TU Delft

Quantum computing is an emerging technology that has the potential to radically change the way we will be solving computational problems in the future. One of the first quantum algorithms with potential impact on real-world applications is Shor’s integer factorization algorithm which might bring an end to public-key cryptography schemes once quantum computers have reached a maturity level that will allow the execution of practical quantum algorithms with a sufficiently large number of qubits. But what about the many compute-intensive tasks we are facing day in and day out in scientific computing, e.g., the solution of linear systems of equations stemming from the discretization of differential equations?

In this seminar talk we will start with a brief review of the main concepts of quantum computing that form the basis of the potential advantage of quantum computers over classical computers. Next, I will introduce the cross-platform programming framework LibKet that is being developed in our group. LibKet is an open-source C++ template library that enables the development of quantum algorithms as platform-agnostic expressions and provides a unified programming interface to execute them on many different quantum-computing simulators and quantum hardware backends in the cloud. Our primary target group are scientists and practitioners who are not quantum experts and want to explore the opportunities of quantum computing as next-generation acceleration technology.
In the second part of the talk, we will discuss a hybrid quantum-classical algorithm for solving linear systems of equations and, in particular, discuss approaches to apply it to the solution of Poisson’s problem in the context of finite element discretizations. If time permits, we will finally discuss a novel approach to generate resource-efficient quantum circuits that can be directly executed on today’s Noisy Intermediate-Scale Quantum computers. The core idea consists in replacing all software-visible high-level quantum gates by parametrized native gates (e.g., single-qubit rotation gates) and treat the problem of generating hardware-optimized executable circuits as design optimization problem.

Short bio: Dr. rer. nat. Matthias Möller is Associated Professor at the Department of Applied Mathematics at Delft University of Technology. He obtained a Diploma in Mathematics from the Faculty of Mathematics at TU Dortmund University, Germany, in 2003 and received a PhD from the same institution in 2008. He joined the Numerical Analysis group at TU Delft in 2013.
His research interests focus on numerical methods for partial differential equations and their efficient implementation on heterogeneous high-performance computing platforms. He has been working on high-resolution adaptive finite element and isogeometric methods and fast iterative solution techniques, in particular, for convection-dominated transport problems and compressible flows.
Since recently, Matthias is working in the field of quantum-accelerated scientific computing with focus on quantum algorithms for numerical linear algebra and optimization problems.

Advanced Reynolds Stress Modelling of Cooling Flows in Turbomachinery : recent results obtained at ONERA (online seminar - open to public)

Emmanuel Laroche from ONERA. Emmanuel is research engineer in Aerothermal / Heat Transfer within the "Département multi-physique pour l’énergétique"/ High Energy, Aerothermal systems and Turbulence (H.E.A.T).

This seminar will focus on recent results obtained at ONERA on the modelling of turbomachinery cooling flows, using advanced Reynolds Averaged Navier-Stokes (RANS) Models. The main models investigated rely on the innovative elliptic blending approach suggested by Manceau to model flows in the wall region more universally. For film cooling flows, the use of Reynolds Stress models in combination with advanced heat flux models can improve the description of the mixing between the film and the mainstream. This will be illustrated on the Penn State 777 hole configuration, and on a recent hot jet configuration studied at ONERA. Concerning impingement flows, up to now , Reynolds Stress models failed to provide a correct estimation of the impingement heat flux. A recent analysis of a LES carried out with CERFACS on a reference configuration brings an new light on such a behavior and potential cures are discussed.

SMAUG: Spectroscopy of Molecules Accelerated in Uniform Gas flow (online seminar - open to public)

Dr. Eszter Dudás, PhD in astrophysics

Abstract: A state-of-art experimental system, SMAUG has been developed to produce unprecedented infrared spectroscopic reference data that will help planetologists to detect new molecules and reconstruct the vertical structure of the atmosphere of exoplanets. A specially designed small dimension Laval nozzle connected to a compact high enthalpy source equipped with cavity ringdown spectroscopy (CRDS) is used to produce high-resolution infrared spectra of polyatomic molecules in the 1.67 μm region. The experimental setup can operate according to two complementary working regimes to interpret the complex pattern of highly-excited vibrational states of methane.

Short bio: Eszter recently finished her doctorate (2021) in laboratory astrophysics at the Institut of Physics of Rennes, France. She has gained experience in working for more than 4 years on the characterisation of high-energy gas flows, including those from plasma sources, through custom designed de Laval nozzles and is particularly interested in the computation and characterisation of flows through and around novel objects.

Towards large-scale optimization of turbomachinery with the discrete adjoint method: from single to multi approach (open to public)

Dr. Matteo Pini from TU Delft

Adjoint-based design methods for turbomachinery are usually based on the assumption of steady state flow to mitigate computational costs. However, because of the inherently unsteady nature of turbomachinery flows and the growing demand for multidisciplinary design capabilities, it is often necessary to resort to time-accurate flow calculations. In this context, reduced order methods have been investigated as a possible cost-effective alternative to time-accurate simulations. The harmonic balance (HB) method, based on spectral discretization in time of the unsteady flow equations, is particularly attractive for the analysis of non-linear dynamic problems dominated by a known set of frequencies, a problem typically encountered in turbomachinery. Thanks to the HB formulation, the time-dependent flow governing equations can be casted in pseudo-steady form, enabling the application of steady adjoint methods to unsteady flow design problems and paving the way to multi-disciplinary design optimization.

Stemming from simple considerations, we will firstly discuss the challenges associated to shape optimization of turbomachinery and learn why the adjoint method is highly suited for large-scale optimization problems. We will then dive into unsteady design problems and show how these can be effectively tackled with the discrete adjoint method. Finally, we will present and discuss the lessons learned from the development of adjoint-based optimization methods for unsteady flow design problems within the SU2 open-source software. To this end, we will show several examples to provide quantitative insight on the capability of the methods for aerodynamic and aero-elastic design optimization of turbomachinery. We will close the talk by providing our view on the next research steps and long-term perspective.

The two-phase flows addressed in this presentation includes the flashing injection in the combustion chamber, the film cooling of small rocket engines and the sloshing investigation. Different techniques will be presented aiming quantitative measurements of liquid temperature, velocity and thickness and free surface characterization in the aforementioned two-phase flows.

The conditions for such techniques to be applied in flight demonstrators will be considered for an open discussion!

Optical techniques for multi-phase systems: a support to space propellant behavior (open to public)

Dr. Alessia Simonini, Research Engineer, von Karman Institute

Deep space exploration, robotic and humans, need to be supported by efficient space engines. Several two-phase flows problematics need to be investigated in such systems to increase their reliability and reduce safety margins. Numerical codes and reduced models, used for the design of space systems, need a strong support for validation by means of experimental databases. Optical techniques might serve to this scope: they can provide a new insight on two-phase phenomena happening at low TRL providing a unique database of test cases.

The two-phase flows addressed in this presentation includes the flashing injection in the combustion chamber, the film cooling of small rocket engines and the sloshing investigation. Different techniques will be presented aiming quantitative measurements of liquid temperature, velocity and thickness and free surface characterization in the aforementioned two-phase flows.

The conditions for such techniques to be applied in flight demonstrators will be considered for an open discussion!

Moment Methods for Non-Equilibrium Low-Temperature Plasmas with Application to Electric Propulsion (open to public)

PhD Defense of Stefano Boccelli, Collaborative PhD VKI/Politecnico di Milano,

Electric space propulsion devices are able to outperform the efficiency of classical chemical rockets, by showing a much higher specific impulse. This has profound effects on the spacecraft design, as significantly more mass can be destined to the payload with respect to the previous technologies. The Hall effect thruster is one of the most employed electric propulsion devices and is based on low-temperature plasma technology. While Hall thrusters have been successfully employed for decades, the design of up- or down-scaled Hall thrusters for future manned missions and for micro-satellites requires renewed modeling efforts. Due to the low pressure of the space environment, together with the presence of electric and magnetic fields, these devices show strong deviations from thermodynamic equilibrium. An accurate computer modeling requires such effects to be carefully considered.

This work discusses the application of the Maximum-Entropy moment methods to such non-equilibrium conditions. In particular, the order-4 Maximum-Entropy methods will be considered, resulting in a set of 14 moment equations that extend the validity of the classical Euler/Navier-Stokes-Fourier fluid formulations towards strong non-equilibrium conditions. After briefly discussing the structure and properties of the 14-moment method, it will be shown that such formulation allows to describe accurately both the low-collisional ion dynamics inside the thruster channel and the strongly anisotropic and asymmetric electron distribution function in presence of crossed electric and magnetic fields. The computational cost of the method appears larger than the simpler fluid methods, but still advantageous with respect to more expensive fully-kinetic simulations.

The work was carried at Politecnico di Milano, in collaboration with the von Karman Institute for Fluid Dynamics. The work have also benefited from visits at the Laboratoire de Physique des Plasmas (LPP, Paris) and at the University of Ottawa.

Turning Data into Value - Sustainability through Probabilistic Analytics (open to public)

Dr. Georg Rollmann , Siemens Energy, Germany

Georg Rollmann has been working on Data Science methodologies ad applications to Gas Turbines R&D and Service business and other areas of the power generation industry for more than 14 years. He is responsible for the Technology Field “Data Analytics & AI” across Siemens Energy leading a cross-organizational team of experts.

Abstract: Across all areas in the energy business, sustainability and reliability aspects are becoming more and more important. For example, power plant operators are looking for condition-based maintenance concepts and optimized products and solutions to fit their specific needs in the heterogeneous energy landscape. For this, a good understanding of the potential failure modes and associated risks is inevitable. A key challenge here is given by the large number of uncertainties from different sources that influence system behavior, such as manufacturing variations, material imperfections, and power plant operating conditions. The Probabilistic approach, that combines domain-specific, e.g. physics-based, modelling with data science and statistical methods, aims at modelling these uncertainties in an explicit way. This allows for more accurate risk assessments and can be leveraged to enable a more sustainable use of natural resources while maintaining, or even improving, system reliability.

Recent advances in variational data assimilation at CMRE (open to public)

Dr. Paolo Oddo, CMRE, Centre for Maritime Research and Experimentation, Italy

Data assimilation is here introduced in its variational formulation as used at CMRE. The classical stationary formulation of the variational cost function is then augmented by including the information retrieved from ensemble simulations to improve the adherence of the background error covariance matrix to the time-evolving regime-dependent errors. The hybrid scheme is used to both correct the systematic error and to improve the representation of small-scale errors in the background error covariance matrix. Optimal exploitation of remotely sensed data is also investigated. To this end, the “hybrid” variational scheme is modified relaxing the usual assumption of uncorrelated observation errors, and physics or statistical based bias procedures are proposed and assessed. Furthermore, the “adjoint free” version of selected observation operators is tested using a new data-driven approach, based on canonical correlation analysis or neural network, to assimilate remotely observed quantities. Real or synthetic experiments data are used to illustrate the benefit deriving from the recent developments.

ARGO: a high order multiphysics solver (open to public)

Dr. Pierre Schrooyen, Senior Research engineer at Cenaero (VKI graduates, PhD UCL)

Pierre's talk will present the Argo platform, which is a multi-physics code based on Discontinous Galerkin discretization. Discontinuous Galerkin methods provides high order accuracy on unstructured meshes while ensuring local conservation of physical quantities. This type of method handles a wide variety of elements types and are well suited for local adaptation in mesh size and interpolation order. The method will be briefly presented and the current capabilities and limitations of the Argo software will be discussed.

Since his graduation, Pierre has been working as a research engineer at CENAERO and is also an invited professor at UCL, giving the Aerospace dynamics course. He is collaborating with VKI since his PhD work on several research projects, further developing ARGO.

Online Seminar on MLOps – the data science solution to efficiently manage the full lifecycle of computational software in the Cloud (open to public)

Dr. David Vanden Abeele, partner and senior quantitative modeller at Credo Software and Radovan Parrák, Data Scientist and YQ product owner

Developing, testing, deploying, running, monitoring and maintaining a computational code on your own PC is easy.

Doing it with a team is harder.

Doing it with a team on a cluster is even harder.

Doing it with a team on a cluster for tens or hundreds of codes simultaneously becomes a complete mess unless you are organized for it and supported by adequate tooling.

The good news is that you are not alone! This problem also appears in Data Science, where things are even worse. ‘Machine Learning Operations’ (MLOps, the Data Science equivalent of DevOps) offers a promising solution to these challenges in the Cloud. This talk discusses the benefits and pitfalls of building and deploying computational software in an MLOps fashion, based on practical experiences in the financial sector, on AWS and Azure Cloud platforms.

Online Seminar on shock-layer radiative heating for the Mars 2020 mission, which just delivered the Perseverance Rover on 18 February this year (open to public)

Dr. Christopher Johnston from NASA Langley Research Center 

The impact of shock-layer radiative heating to the backshell of capsules entering Earth or Mars was assumed negligible until less than 10 years ago. Since then, modeling improvements and new experimental data have shown that radiative heating is actually the dominant heating contributor, relative to convective, over much of the backshell surface. This talk presents the story of how this backshell radiative heating component was ignored for so long for Mars entry, how it was discovered, and how its modeling was refined and utilized for Mars 2020.

Chris Johnston has worked at NASA Langley since 2006, with the main focus of modeling shock-layer radiative heating. He is the primary author of the HARA radiation code, which is one NASA’s standard aerothermal tools. Has worked on the Mars 2020 and Orion programs, and is currently working on the Mars Sample Return Earth Entry vehicle.


Online Seminar on SU2-NEMO: an open-source framework for nonequilibrium flows (open to public)

Prof. Marco Fossati from the University of Strathclyde

Prof. Fossati is associate professor in computational aerodynamics and the head of the Future Air-Space Transportation Technologies Laboratory. His research interests are in the area of multiphysics computational aerodynamics, and his expertise is in the field of aircraft aerodynamics and non-equilibrium flows, modal-based Reduced Order Modeling for aircraft aerodynamics, mesh optimisation and generation.

The talk will give an overview on the developments of an open-source code to address high-enthalpy non-equilibrium flows called SU2-NEMO. NEMO is the outcome of a collaborative effort between the University of Strathclyde, the VKI, Stanford University, and the University of Arizona. The rationale behind NEMO is to develop open-source simulation capabilities to address nonequilibrium physics such as finite-rate chemistry and nonequilibrium energy transfer that characterise the aerothermodynamic interaction of objects flying at high Mach regimes.

Online Seminar on Machine Learning Moment Closures for Accurate and Efficient Simulation of Polydisperse Evaporating Sprays (open to public)

Dr. James B.Scoggins, Postdoctoral researcher at the von Karman Institute

Dr. James B. Scoggins to the AR seminar, where he will talk about his paper presented at this year's AIAA SciTech conference:Machine Learning Moment Closures for Accurate and Efficient Simulation of Polydisperse Evaporating Sprays

He will present a novel machine learning moment method for the closure of the moment transport equations associated with the solution of the Williams-Boltzmann equation for polydisperse, evaporating sprays. The method utilizes neural networks to learn optimal closures approximating the dynamics of the kinetic equation using a supervised learning approach. The neural network closure is compared to reference solutions obtained using a Lagrangian random particle method as well as two other state-of-the-art closure models, based on the maximum entropy assumption. Results on 0D and 1D test cases demonstrate that the closures obtained using the machine learning approach is significantly more accurate than the maximum entropy closures with comparable CPU performance. This suggests that such models can be used to replace expensive Lagrangian techniques with similar accuracy at far less cost.

Online Seminar on Characterization of Supersaturated Nitrogen In Hypersonic Wind Tunnels & The Design Of A Fast-Acting Valve In ANDLM6QT (restricted to VKI member)

Erik Hoberg, PhD at University of Notre Dame, USA 

Erik is PhD candidate at the University of Notre Dame and he received the 2020 BAEF fellowship to study for 6 months at VKI

Erik received his bachelors degree in aerospace engineering in 2017 at New Mexico State University and his masters in aerospace engineering from the University of Notre Dame January of this year. At Notre Dame, he has worked on flow characterization and design in the arc heated hypersonic wind tunnel and the large hypersonic quiet tunnel.

Seminar on Bayesian aerothermal assessments

Pranay Seshadri from Alan Turing Institute, United Kingdom

Pranay Seshadri is the Group Leader in Aeronautics at the Alan Turing Institute — the UK’s national institute for data science artificial intelligence. He is concurrently a Research Fellow in the Department of Mathematics at Imperial College London. He obtained his PhD in 2016 from the University of Cambridge in robust turbomachinery design. After his approx. 30min talk, Pranay will continue with a mini-workshop on 'equadratures': an open-source code for uncertainty quantification, data-driven dimension reduction, surrogate-based design optimisation and numerical integration. The workshop will finish around 15:00.

Abstract of the talk and mini-workshop:

Abstract (for talk):

In this talk, I will give you an overview of my group’s research that is broadly focused on Bayesian aerothermal measurements — the science and statistics of inferring aerothermal quantities. The “Bayesian” perspective arises from both uncertainties in the measurements and uncertainties in regions where we do not have measurements. I will present two case studies of some of the underlying research that cuts across statistics and aerodynamics. The first case study is the measurement of jet-engine sub-system (fans, compressors, turbines, etc.) efficiencies, where the measurements are sparsely placed pressure and temperature rakes. The second case study is the quantification of density from old Schlieren images, where the sensors are densely sampled pixels that measure the refractive index gradient field.

Abstract (for mini-workshop):

This mini-workshop is focused on ‘equadratures’: an open-source code for uncertainty quantification, data-driven dimension reduction, surrogate-based design optimisation and numerical integration (see: https://equadratures.org/). Although we will not have time for tandem coding, I will aim to show code snippets for some of the aforementioned capabilities, so you can try running the code on your own data-sets. There will be quite a few turbomachinery examples presented, including your very own LS-89.

Design challenge for re-entry vehicles: ablation, shape change and aerodynamic performance during re-entry