LES wall treatment method

[ztdepztdep]

I've noticed that there are several LES (Large Eddy Simulation) models implemented in Neko. Could someone please provide some information about the wall treatment method used in these LES models?
Given that wall models are typically only applied to axis - parallel cases, does this imply that they cannot be used for other, more complex problems?
Does it support Spectral vanishing viscosity (SVV) .

[timofeymukha]

Hi. So, first off, the wall modelling capabilities are more or less a work in progress, so if you choose to use that now, be prepared to be on the bleeding edge of development, with all that this entails (lack of proper V&V, breaking changes, etc.). You are correct, the wall_model boundary conditions (and the underlying shear_stress one) currently only work on planar boundaries allied with a coordinate plane. They will not work for any other type of boundary at the moment. We are working on extending this, since this is a severe limitation, of course.

That said, there are two wall models (on the CPU only): Spalding's model and the rough log law. Use the former for smooth walls and the latter for rough.

I am not an expert on SVV, but it is not a wall model, it is something that is applied in the interior in order to stabilize the simulation by applying dissipation to high-frequency modes. This is not implemented in Neko, and neither is any other modal filtering at the moment. However, we have several SGS models implemented, that provide enough dissipation to keep things stable.

[Shiyu-Sandy-Du]

Maybe one more comment: an elementwise modal filter is applied to Dynamic Smagorinsky model. But it's totally different from SVV.