Learning Forum

[smalbro93]

I have been searching online for quite a while and I am completely puzzled.nI understand that we need to enable something called Data Sampling to get the Mean Velocity.nI am doing RANS simulation and don't see Data Sampling anywhere, does it mean that we cannot obtain Mean Velocity Contour for RANS simulation? I know that we need to have a way to get Mean Velocity, I would be grateful if someone could guide me to the right direction or point out some resources.nAnd what is the correct method to obtain the Mean Velocity in case of an Unsteady Simulation?.

[Rob]

If you don't turn on data sampling there is no RMS data calculated. The current velocity is what you are seeing. nFor a transient case, and assuming a mean velocity is a valid value run for a while (ie until the flow field is stable) and then turn on the sampling and run for a while more (ie a few flow cycles). n

[smalbro93]

nHi Rob, thank you for your reply. Does it mean that we cannot obtain mean velocity for Steady Simulation? n

[Rob]

No, just that you'd need to do data sampling. Steady state is the equilibrium case, so, in theory all the results are averaged (look up what RANS means). n

[smalbro93]

No, just that you'd need to do data sampling. Steady state is the equilibrium case, so, in theory all the results are averaged (look up what RANS means)./forum/discussion/comment/98489#Comment_98489

Hi Rob, thank you for replying. I understand that for steady case, the obtained wind velocity is already the mean velocity. So that means when I generate Velocity Magnitude contour, it itself is the Mean Velocity Contour right? Or do I run the Steady Case first and then then do Data sampling with Unsteady to obtain the Mean Velocity Magnitude?n

[Rob]

The velocity contour is the velocity field for that iteration in steady state. Data sampling can also be done on a steady case where we may see some slight changes in the flow (you'll have poor convergence) which can then produce an averaged velocity field. nAs well as needing care with the set up & physics simulation also needs care with language: a term we use may not be understood in the same way by everyone. n

[smalbro93]

Thank you Rob. I am not sure I understood that completely but I really appreciate your time and have been helped a lot by this Forum. Thank you.n