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cfd-student April 29, 2008 17:59

sinsoudial time varying BC
Hi guys

I am simulating a plane duct flow with time varying total pressure BC at the inlet and outlet is sealed. I have specified an equation at the inlet for this BC.

I am getting a message from solver that "a wall has been placed at the inlet". If I change my inlet BC to opening how would that affect my solution? I am running laminar flow. How else can i resolve the issue? Thank you

Glenn Horrocks April 29, 2008 18:45

Re: sinsoudial time varying BC

Read the documentation about the difference between outlets, inlets and openings. In short inlets and outlets only flow in one direction and place "walls" at the boundary in the case of reverse flow. An opening allows forward or reverse flow.

Glenn Horrocks

cfd-student April 30, 2008 05:23

Re: sinsoudial time varying BC
Thank you Glenn but how the forward/reverse flow can affect the outcome. Any ideas? What if I use non-reflecting BC at the inlet?

Rogerio Fernandes Brito April 30, 2008 21:48

Re: sinsoudial time varying BC
what kind is this problem?? is this a closed cavity? (or a semi-open cavity?)

cfd-student May 1, 2008 19:06

Re: sinsoudial time varying BC
semi-open cavity! I am using following expression at the inlet y=A*sin(omega*t). Inlet is opening, outlet is sealed, side walls are symmetry and upper and lower sides are wall. I have randomily chosen amplitude, omega is in radians per second and time is my time step. I am not getting a sine wave the way I should do. What could be wrong?? Thank you for your help Rogerio and others.


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