[rajasekhar reddy]

Hello all,



we are simulating a multi species setup in our case. we have a room where the Supply volume flow rate is 10360 L/S. our extract volume flow rate is 9320 L/S. so we have a difference of 1040 l/s, which is accumulating in the fluid domain. for now we are using velocity inlet boundary condition at inlets and velocity inlet boundary condition with negative velocity at outlets.

in the current case we have to maintain a positive pressure in the fluid domain. so, we are supplying more inflow compared to outflow.

our simulation is running with not very great convergence of continuity but we are able to achieve some simulation contours.

will anyone please suggest what are the other boundary conditions if the above conditions are not correct.



Also will any one please suggest is there any possible way to maintain positive pressure with mass imbalance in our current simulation.

[vinerm]

A combination of velocity at both, inlet and outlet, is not an appropriate set of boundary conditions. And for your case, velocity condition is wrong at either of the boundaries. The options you have are mass flow inlet or pressure inlet and similarly mass flow outlet or pressure outlet.

[rajasekhar reddy]

Thankyou Vinerm for your quick response.

i have one more doubt. if for suppose i will match my inlet flowrate with outlet flowrate in the above case. is it possible to use velocity boundary condition at both openings.

Thankyou,
Reddy.

[vinerm]

Theoretically, you can use that combination but you will get into numerical errors with most of the CFD codes. So, it is recommended not to do that.