Navier Stokes solvers for laminar flows are good basis for LES codes. You just have to add a routine for computing the SGS viscosity (Smagorinsky model).

G.

I think its a little more complicated than that!

Not really. Most LES algorithms do not have any explicit filtering, and just asume that your are working with the filtered fields.

Implementations of Smagorinsky SGS model (usually) just compute the SGS viscosity from a measure of the (filtered) deformation tensor.

Dynamic models and Scale Similarity models might be more involved, but 90% of the code is still very much the same as a (good) NS laminar flow solver.

G..

Yes. It's right.

1. Make a 3D Laminar flow analysis code.

2. Test this code for a laminar flow regime.

3. Optimize this code.

4. According to the LES (or filtered) equation, insert (dynamic) Smagorinsky model or SGS model to the Laminar flow analysis code.

5. Increase Reynolds number and mesh density.

6. Run LES code for a turbulent flow

Only the difference is governing equation (= LES equation). But it's not much different. Just adding the eddy viscosity in the Smagorinsky model. Output flow field is filtered flow field.

What about a Favre-filtered LES code, can this be simply created from a non-favre filtered laminar code?

What about inflow boundary condition : I mean, double, triple and so on velocity fluctuation correlations have to be introduce at the inflow, haven't they ?

Does this mean that a laminar code is only laminar because the Reynolds number has been kept low? If the Reynolds number in a Laminar code is increased into the "turbulent" zone, then what happens to the results? Is it nececcary to introduce a turbulence model? k-epsilon? Can someone explain.

Also, in a laminar flow, if using an LES code, should the SGS viscosity be zero (at least in theory)?

As for Sylvain's question beloq regarding correlations, are there any well documented codes available online for creating inflow correlated velcoity data? Are there any code (well documented....this is important for me) for creating isotropic and homogenous turbulence initial fields?