External analysis convergence

[cdumontier]

Help needed.
I'm doing wind analysis with microflo on a hospital campus and I'm having difficulties with the simulation. The variables residual are decreasing slowly but are still high. Mass residual does not decrease at all. It tops the chart at 1e+002; flat line... The site is quite large, about 1 km by 350 m, but fairly open except for a region with weirdly shaped buildings. I split the site in 3 parts to help. The model is imported from sketchup plugin.
I use a 4 meters grid with 1 meter tolerance. Smaller grid makes the application crash, short of memory (too much cells).
False time step, 0.5. The application recommended 0.2, but I increased it to help with the fact that the residuals were decreasing even slower.
And to help with the mass residual, I increased the number of pressure inner iterations from 9 to 20 and even to 100, but makes no difference. Flat line at the top of the chart...
I'm no expert and I'm a bit loss on this one. Can anyone help me with the parameters? Or is something else causing the issues?
Thank you so much.
Cedric

[JBBAILLY]

Hello Cedric,

I encounter the same problem (flat line at top for the mass residual) with an external simulation on a district (1km x 1km).
Did you solve or understand your problem ?

Thank you

Jean-Baptiste

[harshadj]

Mass residuals for external simulation are meaningless as mass is always conserved for an external simulation.

As long as everything else converges or keeps reducing, you are fine.