von Karman Institute Lecture Series and Events

The seminar will be presented by Prof. Corneliu Balan REOROM Laboratory, Politehnica University of Bucharest, Romania

The influence of the surface microgeometry in rheometry is investigated using the correlation between experiments and numerical simulations of the flow in plate – plate rotational geometry. The presence of micropillars or microchannels on the plates induces effective or apparent slip of the fluids at the walls generating a "dynamic hydrophobic surface”. The comparison between the measured torques in smooth and microchannels patterned configurations are analyzed using the numerical simulations performed by the Fluent code for the Newtonian fluid and the Carreau model.

The present study demonstrates that hydrophobic effects can be induced at the walls, without the violation of the no-slip condition, by changing the local flow spectrum due to the presence of patterned surfaces at the solid boundary. The results confirm that computational rheometry is an useful tool not just to interpret the experimental data but to calculate the errors of the measurements, as well as to explore and model flow phenomenon as the apparent slip which manifests for flows at small and moderate Reynolds numbers.

The applications of the paper are not only focused to develop novel testing procedures in rheometry, but also to design micro-patterned surfaces for the control of slip/adherence of simple and complex liquids at solid surfaces of microfluidic devices and immersed bodies.

Location : von Karman Institute for Fluid Dynamics, Waterloosesteenweg 72, 1640 Rhode-St-Genèse

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