How to plot turbulent shear stress in Fluent post processing?

cfdnewb123 · May 26, 2020, 13:28

I want to plot a graph against turbulent shear stress u'v'. It is not the same as wall shear stress which option already exists and I have already plot that.

vinerm · May 26, 2020, 15:48

What do you mean by Fluent Post-Processing? Is it within Fluent or CFDPost? If you are using Workbench and opened the tool using Results cell, then it is CFDPost. Reynolds stress is nothing but the turbulent kinetic energy, if you are using EVM. If you are using RSM, then it is directly available for plotting. So, it depends on the turbulence model being used.

cfdnewb123 · May 26, 2020, 22:04

Thanks for the response. Yes I am using CFDPost. However, when I try turbulence kinetic energy, it gives me result different from experiment. Is turbulence kinetic energy the same as turbulence shear stress? I thought TKE=0.5 u'u' while anisotropic TSS=u'v'?
If EVM doesn't provide the TKE as you mentioned, I can define this field by myself. However, do you know where can I define the TSS on CFD-Post? It doesn't have Fluent's UDF.

cfdnewb123 · May 26, 2020, 23:29

Never mind. I resolve this already. Thanks

vinerm · May 27, 2020, 04:23

TKE is neither Reynolds stress nor it is

, at least not for EVM. What I meant was that you can calculate it using k because Reynolds stress is $\rho u'v'$ and k is based on

. However, for isotropic turbulence, Reynolds stress tensor has all its six components equal to each other. Therefore, you can determine it using $(2/3)\rho k$ . Do note that this is magnitude and implies no direction. You cannot define k yourself since a conservation equation is solved for it and EVM always provides k (turbulent kinetic energy). In CFDPost, you need to define an expression and then assign this to a new variable.

whistling · November 9, 2021, 05:45

Quote:

Originally Posted by cfdnewb123

Never mind. I resolve this already. Thanks

Hi, I have to do the same thing. Could you please tell me how to do?

May 26, 2020, 13:28	How to plot turbulent shear stress in Fluent post processing?	#1
cfdnewb123 Member Join Date: Feb 2019 Posts: 69 Rep Power: 7	I want to plot a graph against turbulent shear stress u'v'. It is not the same as wall shear stress which option already exists and I have already plot that.

May 26, 2020, 15:48	Reynolds Stress	#2
vinerm Senior Member Vinerm Join Date: Jun 2009 Location: Nederland Posts: 2,946 Blog Entries: 1 Rep Power: 36	What do you mean by Fluent Post-Processing? Is it within Fluent or CFDPost? If you are using Workbench and opened the tool using Results cell, then it is CFDPost. Reynolds stress is nothing but the turbulent kinetic energy, if you are using EVM. If you are using RSM, then it is directly available for plotting. So, it depends on the turbulence model being used. __________________ Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority.

May 27, 2020, 04:23	Reynolds Stress	#5
vinerm Senior Member Vinerm Join Date: Jun 2009 Location: Nederland Posts: 2,946 Blog Entries: 1 Rep Power: 36	TKE is neither Reynolds stress nor it is , at least not for EVM. What I meant was that you can calculate it using k because Reynolds stress is $\rho u'v'$ and k is based on . However, for isotropic turbulence, Reynolds stress tensor has all its six components equal to each other. Therefore, you can determine it using $(2/3)\rho k$ . Do note that this is magnitude and implies no direction. You cannot define k yourself since a conservation equation is solved for it and EVM always provides k (turbulent kinetic energy). In CFDPost, you need to define an expression and then assign this to a new variable. cfdnewb123 likes this. __________________ Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority.

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May 26, 2020, 22:04		#3
cfdnewb123 Member Join Date: Feb 2019 Posts: 69 Rep Power: 7	Thanks for the response. Yes I am using CFDPost. However, when I try turbulence kinetic energy, it gives me result different from experiment. Is turbulence kinetic energy the same as turbulence shear stress? I thought TKE=0.5 u'u' while anisotropic TSS=u'v'? If EVM doesn't provide the TKE as you mentioned, I can define this field by myself. However, do you know where can I define the TSS on CFD-Post? It doesn't have Fluent's UDF.

May 26, 2020, 23:29		#4
cfdnewb123 Member Join Date: Feb 2019 Posts: 69 Rep Power: 7	Never mind. I resolve this already. Thanks