Learning Forum

[Prashant Jha]

Hello all

I am simulating rayleigh benard convection with two immiscible layers one on top of another. I have finished my simulations but when I go to post-processing and try to visualise the volume fraction through volume rendering, then I am getting no results. Also, when I plot the contours of volume fractions of different phases, then also I don't get the results. I have attached the screenshots below. Please someone help me out.

[Rob]

Which solver did you use? 

[Prashant Jha]

I have used Fluent

[Rob]

OK. If you open an earlier time result in Fluent how does it look? How did you initialise the solution? How well resolved is the mesh? 

[Prashant Jha]

For variables like pressure, velcoity and temperature, I get the results, just only when I want to see the volume fraction this error comes at any time step. I used standard initialisation from all zones. And the mesh is very fine of size 0.5 mm.

[Rob]

Standard? And no patching? 

So, 50 cells across the domain and they're all square? 

[Prashant Jha]

yeah, i have done patching for the fluids with their respective regions. Number of cells are more, but the quality is very fine, that i checked using evaluate mesh quality option 

[Rob]

The quality metrics are just to tell you the cell quality, mesh quality also includes whether you have sufficient resolution of the flow/phase gradients. 

How did the solution look at an earlier stage? How good was the convergence?

[Prashant Jha]

[Rob]

OK, so very poor convergence. And the mass monitors? Ie how much mass was lost per time step?

[Prashant Jha]

sorry but how to get that

[Rob]

Volume integral, but you'd need to have that set before the run. It's in Report Definitions. 

[Prashant Jha]

so now what to do, how can i visualise my phases? 

 

[Rob]

I don't know if you have any phase to display - hence my suggesting opening an earlier save. I'd post process in Fluent for most tasks now, we very rarely use CFD Post for Fluent now.