Learning Forum

[ztjia]

(1) In some ansys paper i see URANS SST, does it mean SST K-omega? eg: in sttached picture. also, what the SBES means? is it same as SST K-omega with SBES or Transition SST with SBES?

thanks for your help.

[Rob]

We've got several turbulence models, and then several flavours of each of those. So, SST k-w is one of the k-w options, and SBES can then be added to that model.
A starting point would be https://ansyshelp.ansys.com/account/Secured?returnurl=/Views/Secured/corp/v212/en/flu_ug/flu_ug_sec_turb_setup_options.html and https://ansyshelp.ansys.com/account/Secured?returnurl=/Views/Secured/corp/v212/en/flu_th/flu_th_chap_turbulence.html
This would be a little more specific - https://ansyshelp.ansys.com/account/Secured?returnurl=/Views/Secured/corp/v212/en/flu_ug/flu_ug_sdes_set.html

[DrAmine]

(U)RANS-SST: SST Model. That is Just Reynolds Averaging of NS equations.
SBES is hybrid LES-URANS approach: Stress Blended Eddy Simulation Model.-Best in class when it comes or Scale Resolving Simulation Approaches.
The manual does contain all details. That is the first address when users are looking after help :)

[ztjia]

thanks for your reply, but i am confused on the use of SST in fluent. in some paper, they use SST model in CFX, but in fluent , i just find SST k-omega, is the SST model in CFX the same as SST k-omega in fluent? in the following picture(Brown, 2020, Application of hybrid RANS-LES models to the prediction of flow behaviour in an industrial crystalliser.), the researcher used SST-SDES and SBES model in CFX, does it mean SST k-omega with SDES or SBES?

[ztjia]

recently, i also meet a question that when i use unsteady simulation, after a while, the residual picture will become blank, all the monitor picture in the console will get blank just like the following picture. and i have checked the simulation, the simulation is always going on.

[ztjia]

[DrAmine]

SST is SST k-omega are referring to the same turbulence model in Ansys CFX and Ansys Fluent (which are different solvers).

[DrAmine]

You better try first to update graphic card driver and check if you are using at least a professional card and not a chip.
Graphics Cards Tested (ansys.com)

[ztjia]

Thanks for you reply,I will try it.

[ztjia]

About the use of SBES shielding function in stirred tank
The stirred tank is simulated by K-omega SST-SBES in fluent.The stirred tank is divided into two parts, sationary part and rotate part. SM(sliding mesh) was used to simulate the rotating of impeller.The sationary part and rotate part are connected by the way of interface.
After transient simulation, The schematic diagram of the shielding function from the monitored y=0 plane reveals that the shielding function appears to be 1 at the junction of the slip grid, which should normally be 0 at all locations except for the boundary. How can this phenomenon be eliminated?

[aitor.amatriain]

Have you checked the mesh quality and the residuals there? I have faced these problems when the mesh was too coarse or the simulation was not converging well.

[ztjia]

thanks for your reply. I have checked the residuals, there is no problem. The grid above the interface is fully co-nodal. The graph below shows the axial velocity variation of the monitoring point. As for the mesh quality, I will check it again, hope to discuss with you later.

[ztjia]

Hello´╝îAitor
I have checked the residual, all components reach the creteria 10e-3. The mesh quality of minimum Orthogonal Quality is 0.47, and I have improved the poor Quality cells, all the cells with orthogonal quality are above 0.667. but the phenomenon still exists. After transient simulation, The schematic diagram of the shielding function from the monitored y=0 plane reveals that the shielding function appears to be 1 at the junction of the slip grid, which should normally be 0 at all locations except for the boundary.
Is there any other reason for this phenomenon? Hope for your help, Aitor.