Velocity Magnitude for Steady state RANS
While performing a steady state RANS CFD simulation with RNG k-ε turbulence model in Ansys Fluent, if I plot the velocity magnitude (V = SQRT(Ux^2 + Uy^2 + Uz^2) ) at a random point within the computational domain, does this velocity magnitude represents the mean and fluctuating velocity components or is it just representing the mean velocity at that particular point?:confused:
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only the mean
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Is my interpretation of your statement correct? |
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Yes. The "velocity" that you get when you do RANS is only the mean velocity. RANS means Reynolds-averaged Navier Stokes. When you solve RANS, you are not solving the time-accurate Navier Stokes equations but the Reynolds-averaged ones, written in terms of the reynolds-averaged variables (which you are calling the time average velocity). If you do URANS (unsteady RANS) you still get unsteady reynolds-averaged, which is averaged over a finite T instead of infinite T. Here the velocity you get is still the reynolds-averaged velocity (containing no fluctuating part), although it does vary in time slowly. |
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