Reply To: External wind flow through a building

[Jason Sum]

Hi Rob, based on your guidance, I have included the ABL (by UDF) for my building aerodynamics case to account for the roughness of urban terrain at the upstream.

Through a steady-state simulation with ABL inlet, the continuity residual still fluctuated between 1e0 ~ 1e-1 without converging.

 
As mentioned, BOI refinement made to capture wake and leeward side, Face refinement for building and ground surface
Maximum Aspect Ratio = ~39 (high aspect ratio mostly happen in inflation layers of building edges)
Minimum Orthogonal Quality of: 0.30 

Mass imbalance and pressure monitored at a point near rooftop (per 5 iter) also did not obtain consistent values as simulation going on. And turbulent viscosity limited to viscosity ratio of 1.000000e+05 without decreasing.

I am confused, in this case should I keep working on improving mesh quality for steady state continuity convergence, OR look for a transient process as the flow phenomenon in this case may be dynamically changing and hardly reaching a steady outcome? Is it possible that no steady state convergence because the building flow and wake oscillate (e.g. shedding)? 

Kindly hope for your experienced and comprehensive guide on this, such issue struggled me a lot!! Mush appreciate!