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

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Old   November 19, 2012, 02:50
Smile How to get a plot of fluctuating velocity component{u'(t)} in a turbulent flow
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How can we plot fluctuating component of velocity {u'(t)} in a turbulent flow in a channel with respect to time at a point.

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TQIM
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Old   November 19, 2012, 11:34
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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?
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Old   January 25, 2014, 03:52
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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


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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?
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Old   October 16, 2014, 12:30
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Quote:
Originally Posted by aqua View Post
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?
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Old   October 18, 2014, 12:10
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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.
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Old   November 10, 2014, 11:34
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Quote:
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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.
See also Article Number 3668 in the Steve Portal.
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Old   November 10, 2014, 18:51
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See also Article Number 3668 in the Steve Portal.

AHHH thanks!!!
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Old   November 11, 2014, 11:22
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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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