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

TQIM · November 19, 2012, 01:50

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, 10:34

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, 02:52

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.

How to define that field function? Please help and thank you!

Aqua

Quote:

Originally Posted by triple_r

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

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, 10:34

Quote:

Originally Posted by cwl

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.

SB123 · November 10, 2014, 17:51

Quote:

Originally Posted by gravis

See also Article Number 3668 in the Steve Portal.

AHHH thanks!!!

SB123 · November 11, 2014, 10:22

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

November 19, 2012, 01:50	How to get a plot of fluctuating velocity component{u'(t)} in a turbulent flow	#1
TQIM New Member Taryk Join Date: Nov 2012 Posts: 9 Rep Power: 14	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

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
CFX Treatment of Laminar and Turbulent Flows	Jade M	CFX	18	September 15, 2022 07:08
Turbulent flow through a pipe with variable inlet velocity	lobstar	OpenFOAM Running, Solving & CFD	8	March 28, 2012 11:15
ATTENTION! Reliability problems in CFX 5.7	Joseph	CFX	14	April 20, 2010 15:45
Reynolds and Turbulent flow	Frederic Dubinski	CFX	5	October 21, 2004 04:12

November 19, 2012, 10:34		#2
triple_r Senior Member Reza Join Date: Mar 2009 Location: Appleton, WI Posts: 116 Rep Power: 18	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?

October 18, 2014, 12:10		#5
cwl Senior Member Chaotic Water Join Date: Jul 2012 Location: Elgrin Fau Posts: 438 Rep Power: 18	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.

November 11, 2014, 10:22		#8
SB123 Member Join Date: Mar 2013 Posts: 42 Rep Power: 14	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