muEff and mut/sigmat

Tobi · November 11, 2012, 07:33

Hi all,

I have a simple question to the following two codes:

Code:

     - fvm::laplacian(turbulence->mut()/sigmat, csi)

Code:

     - fvm::laplacian(turbulence->muEff(), csi)

I know that muEff = mu_laminar + mu_turbulent. So I thought that in the first code line I am calculating the diffusion term just with the turbulent diffusion and the laminar diffusion is neglected. sigma_t is the turbulent prandtl number = 1

In the second code therefor I am using both of them to calculate the diffusion coefficient.

It would be very useful for me!
Thanks in advance

Regards Tobi

Tobi · November 11, 2012, 08:50

Solved my problem!

sibo · January 28, 2018, 15:57

Quote:

Originally Posted by Tobi

Solved my problem!

Hi Tobias,

I also have this question. Could you help?
1.

Code:

turbulence->muEff()

Does this muEff mean mu_laminar + mu_turbulent?
2.

Quote:

sigma_t is the turbulent prandtl number = 1

Why the sigma_t is the turbulent prandtl number? I thought it should be "Prt" in the code.

Thanks a lot!

babakflame · January 28, 2018, 19:55

Hi Sibo

Although, you have asked Tobias, however, since he is asleep. I am answering you

1)yes you are correct.

muEff = mu_laminar + mu_turbulent

2) It depends on the code. I am aware of some codes that they use sigmat for turbulent Prandtl number.
Always you can change the variable if you don't like it

Regards

sibo · January 28, 2018, 22:03

Hi Babak,

Thanks for the help!

November 11, 2012, 07:33	muEff and mut/sigmat	#1
Tobi Super Moderator Tobias Holzmann Join Date: Oct 2010 Location: Tussenhausen Posts: 2,708 Blog Entries: 6 Rep Power: 51	Hi all, I have a simple question to the following two codes: Code: - fvm::laplacian(turbulence->mut()/sigmat, csi) Code: - fvm::laplacian(turbulence->muEff(), csi) I know that muEff = mu_laminar + mu_turbulent. So I thought that in the first code line I am calculating the diffusion term just with the turbulent diffusion and the laminar diffusion is neglected. sigma_t is the turbulent prandtl number = 1 In the second code therefor I am using both of them to calculate the diffusion coefficient. It would be very useful for me! Thanks in advance Regards Tobi

January 28, 2018, 19:55		#4
babakflame Senior Member Bobby Join Date: Oct 2012 Location: Michigan Posts: 454 Rep Power: 15	Hi Sibo Although, you have asked Tobias, however, since he is asleep. I am answering you 1)yes you are correct. muEff = mu_laminar + mu_turbulent 2) It depends on the code. I am aware of some codes that they use sigmat for turbulent Prandtl number. Always you can change the variable if you don't like it Regards sibo likes this.

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