[madcyclop2]

Have anyone try to do simulation around square cylinder using DES? Or will the result be the same with LES?

Lastly, can fluent run DES simulation?

Thank you.

[som87]

Hi, let me point out that the implementation of DES in Fluent software is an extended k-omega SST (If I am correct, ANSYS 14.0 has similar situation), the main difference being the procedure in which the numerical solver calculates the dissipation term of the turbulent kinetic energy. The widely used constant (=unit value) term in k-ω SST model is further modified in DES, where its value depends on turbulent length scale, calibration constant & the maximum grid spacing. As a result your solution is resolved just like LES as you move far from bluff-body.As far I know, in DES we do not use a subgrid mode like we do in LES.
Now, to cut the chase short, yes fluent can use DES simulation

[cfdnewbie]

Originally Posted by madcyclop2

Have anyone try to do simulation around square cylinder using DES? Or will the result be the same with LES?

It is difficult to answer that question in a general way. Neither the term LES nor the term DES really defines what exactly happens, or what you are doing in terms of numerics and/or models. It is like saying "I own a car", but that just gives the general idea of 4 wheels and a combustion engine, but can range from a 1920s Ford to a Lamborghini.

So, in very broad terms: No, I wouldn't expect the DES and the LES approach to give the same result (one would have to define what you mean by the "same" ), as different LES approaches will already give you completely different results.

You will certainly get a result with both DES and LES, but how to interpret the validity of it will be tricky.