[a.hazarika]

Dear All Members,

I have across a case where for the same geometry ,operating conditions the flow pattern completely diverged from Parallel flow field using SIMPLE pressure-velocity coupling scheme to Merging flow field using COUPLED scheme for a dual Rushton stirred vessel . Now I am confused about which result to consider and am not able to explain as to why I am getting such a huge difference in the flow-field with change in Pressure-Velocity coupling. Experimental validation is not possible in this case.

Could you kindly provide me some insight and feedback in this regard? Looking forward to hearing from you.

Kind Regards,
Abhinav Hazarika

[vinerm]

It is quite possible that the results from both cases are wrong and reasons could be anything from mesh, material properties, models, to numerical schemes and convergence. Usual procedure is to start checking from the top, i.e., mesh quality, however, for your case, I'd recommend start from the bottom. Check if both the cases are well converged. If the speed is on the lower side, you may have to run a transient simulation. However, if it is high enough, higher than say 5 Hz, steady-state may work.

For rotating machines, coupled is preferred scheme and should require lesser number of iterations to reach convergence, provided it reaches there. Use only higher order schemes for all fields.