[enganas]

Dear all,
I am using Numeca Fine/open.

In the output section, which includes all the relevant variables you want to compute, such as velocity, vorticity, TKE, dissipation etc....

However, if I am interested in calculating the Turbulence Intensity. How can I do that?
Secondly, it doesn't show in the output the fluctuations u' v' w'.

I am interested in the fluctuations to calculate the TI, Re stresses and other turbulence properties.

Could anyone inform me how can I get access to these fluctuations.

Thanks,

enganas

[Hamidzoka]

Hi;
If Isotropic turbulence models based on Boussinesq hypothesis are used (like K-epsilon, K-omega,...) Reynolds stress components as well as TI are calculated based on K itself and mean flow velocities. In other words, this hypothesis tries to model Reynolds stresses rather than calculating them. In this case all normal components of Reynolds stresses are equal. That's why they are called isotropic models.
Only in anisotropic turbulence models like RSM, Reynolds stresses are explicitly calculated, definitely at higher computational costs, and can be used directly in post-process and calculation of TI.

Regards

[enganas]

Originally Posted by Hamidzoka

Hi;
If Isotropic turbulence models based on Boussinesq hypothesis are used (like K-epsilon, K-omega,...) Reynolds stress components as well as TI are calculated based on K itself and mean flow velocities. In other words, this hypothesis tries to model Reynolds stresses rather than calculating them. In this case all normal components of Reynolds stresses are equal. That's why they are called isotropic models.
Only in anisotropic turbulence models like RSM, Reynolds stresses are explicitly calculated, definitely at higher computational costs, and can be used directly in post-process and calculation of TI.

Regards

Dear Hamidzoka,
Thanks for your reply.
In my simulations am using k-omega SST.

Can I obtain the TI from TKE data. is there any relation I can find.

Thanks,

[Hamidzoka]

Hi;
One simple relation is "sqrt(2/3*K)/(Mean velocity Magnitude)".
More descriptions can be found in the literature.

Regards