Turbulence over textured surfaces

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• Ricardo Garcia Mayoral
• Wednesday 05 February 2025, 14:00-15:00
• JDB Seminar RM.

If you have a question about this talk, please contact Anna Walczyk.

This talk will present an overview of the understanding our group has gained in the last 5-10 years on the interaction of surface texture in general with wall turbulence. I will argue that this interaction occurs essentially through two physical mechanisms. In the first, surface texture imposes a set of effective, homogeneous boundary conditions on the overlying, texture-incoherent background turbulence. The effect of inertia and the lack of separation of scales between the texture and the turbulent eddies are then key features. When the resulting transpiration effect is small, slip dominates, turbulence remains smooth-wall-like and the effective boundary conditions give rise to Paolo Luchini’s `protrusion-height’ regime. When the transpiration effect is large, it can account on its own for the changes in the overlying turbulence, as is the case for high-permeability porous substrates. The second mechanism is the non-linear interaction of the texture-coherent flow with the overlying, texture-incoherent turbulence, which acts on the latter as a forcing term altering the momentum equations. This term can be added back into texture-less simulations, and is sufficient to capture the effect of the texture granularity on the overlying turbulence.

This talk is part of the Engineering Fluids Group Seminar series.

This talk is included in these lists:

• Acoustics Lab Seminars
• Engineering Department Acoustics/Combustion Student seminars
• Engineering Fluids Group Seminar
• JDB Seminar RM

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