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 TQIM November 19, 2012 02:50

How to get a plot of fluctuating velocity component{u'(t)} in a turbulent flow

How can we plot fluctuating component of velocity {u'(t)} in a turbulent flow in a channel with respect to time at a point.

Regards
TQIM

 triple_r November 19, 2012 11:34

You can create a probe under derived parts and monitor the velocity, or define a field function equal to the velocity minus the average velocity, and then monitor that, but you need to have a value for the average velocity, and that means you should have run the simulation for a long enough time that you have a statistically converged value for the mean velocity. Are you using LES, DES, or DNS?

 aqua January 25, 2014 03:52

Hi, Can I ask a similar question please: I am using LES to perform simulation around a cylinder. To compare the results from LES to a time averaged simulation result (like RANS), I would like to plot a scalar of the mean pressure from the LES transient results.

So, I will need to define a filed function, which means, the time average pressure of each point for a certain time.

Aqua

Quote:
 Originally Posted by triple_r (Post 392997) You can create a probe under derived parts and monitor the velocity, or define a field function equal to the velocity minus the average velocity, and then monitor that, but you need to have a value for the average velocity, and that means you should have run the simulation for a long enough time that you have a statistically converged value for the mean velocity. Are you using LES, DES, or DNS?

 SB123 October 16, 2014 12:30

Quote:
 Originally Posted by aqua (Post 471705) Hi, Can I ask a similar question please: I am using LES to perform simulation around a cylinder. To compare the results from LES to a time averaged simulation result (like RANS), I would like to plot a scalar of the mean pressure from the LES transient results. So, I will need to define a filed function, which means, the time average pressure of each point for a certain time. How to define that field function? Please help and thank you! Aqua
i agree with aqua, i'd liek to do this too?

 cwl October 18, 2014 12:10

I guess Monitors -> <Right-Click> -> Field Mean/Variance Monitor might help - depends on value you are trying to estimate; where Field Function argument of Monitor should be Report in specfifc volume of interest.

 gravis November 10, 2014 11:34

Quote:
 Originally Posted by cwl (Post 514966) I guess Monitors -> -> Field Mean/Variance Monitor might help - depends on value you are trying to estimate; where Field Function argument of Monitor should be Report in specfifc volume of interest.

 SB123 November 10, 2014 18:51

Quote:
 Originally Posted by gravis (Post 518362) See also Article Number 3668 in the Steve Portal.

AHHH thanks!!!:D

 SB123 November 11, 2014 11:22

so this does a field function, or average parameter. how would one go about plotting a average velocity contour map, ie create scalar scene velocity across flow regime along plane C/S. and it varies with each time step... (duh), but then take all of those and create average over entire simulation

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