outflow boundar condition problem, mutiphase flow

ziemowitzima · April 29, 2012, 15:11

Hello,
I am doing some multiphase flow computations using twoLiquidMixigFoam solver.
Simulation (see attached figure:
computational_domain.jpg
calculates flow with inflow (emergency valves inflow of the fluid1 to the tunnel filled with fluid2 ) and outfolw from the tunnel.

After fluid1 reaches end of the tunnel a problem appears. Because there is a "recirculation zone" trying to leave the tunnel , imposed boundary conditions does not allow it to leave the computational domain, see attached next 3 figures for different time :
recirculation_time_1.jpg
recirculation_time_2.jpg
recirculation_time_3.jpg
I was trying many different BC for velocity (zeroGradient, InletOutlet, mixedDirections) but result/problem is the same...

Does any one know if there is some simple (or any using proper BC) solution for this problem ? To just allow fluid to leave domain, without doing mass at the outflow ??

Best

ziemowitzima · April 29, 2012, 15:27

interesting is , that after setting (gravity) g = 0, problem disappears ...

April 29, 2012, 15:11	outflow boundar condition problem, mutiphase flow	#1
ziemowitzima Senior Member Mieszko Młody Join Date: Mar 2009 Location: POLAND, USA Posts: 145 Rep Power: 17	Hello, I am doing some multiphase flow computations using twoLiquidMixigFoam solver. Simulation (see attached figure: computational_domain.jpg calculates flow with inflow (emergency valves inflow of the fluid1 to the tunnel filled with fluid2 ) and outfolw from the tunnel. After fluid1 reaches end of the tunnel a problem appears. Because there is a "recirculation zone" trying to leave the tunnel , imposed boundary conditions does not allow it to leave the computational domain, see attached next 3 figures for different time : recirculation_time_1.jpg recirculation_time_2.jpg recirculation_time_3.jpg I was trying many different BC for velocity (zeroGradient, InletOutlet, mixedDirections) but result/problem is the same... Does any one know if there is some simple (or any using proper BC) solution for this problem ? To just allow fluid to leave domain, without doing mass at the outflow ?? Best

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April 29, 2012, 15:27		#2
ziemowitzima Senior Member Mieszko Młody Join Date: Mar 2009 Location: POLAND, USA Posts: 145 Rep Power: 17	interesting is , that after setting (gravity) g = 0, problem disappears ...