I saw an example for simulating turbulent flow by DNS using Fluent. This example in the CFD course at STANFORD UNI. I sent email to the department asking how to do DNS by Fluent but no answer. Could you please if you know how, inform me/us. It is very interesting subject. Best regards. W.A.

To simulate DNS in Fluent you have to use LES model with a suitable grid size. In fact LES is a filtering operation and in the finite volume method used in Fluent is the method that itself implicity provides the filtering operation. In other words with a LES model Fluent directly resolve the eddies that are bigger than the grid size and simulate with the LES subgrid models the eddies that are smaller than the grid size; but if you use a grid size so fine to directly resolve also the smallest eddies of your problem you do a direct numerical simulation (DNS). The order of the grid is several orders of magnitude bigger than a Rans simulation and this requires a very powerful pc.Furthermore you have to use a unsteady simulation. As you know is very complicated to do well a DNS simulation but as you said is a very interesting subject. Hope this helps Regards Emanuele

Your reply is very helpful/useful. Thanks a lot Mr. Emanuele. My best regards. W.A.