How can I apply an outflow boundary condition?

[ChengXiaoSi]

Hi! In the simulation for Rayleigh-Taylor instability, I want to apply an outflow boundary condition in the y-direction. I initially set it to "ZEROGRADIENT," but it failed to achieve the desired effect. Setting it to "SYMMETRY" yielded slightly better results, though still not ideal. How should I configure it to achieve effective outflow conditions?

ZEROGARDIENT
t=0

t=0.6

SYMMETRY
t=0

t=0.6

Thank you!

[dbezgin]

Hi, can you check whether the "SIMPLE_OUTFLOW" boundary condition yields better results? For this, you need to specify a pressure at the outflow boundary.