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James Date March 4, 2001 23:53

Unsteady boundary conditions
I'm modelling a NACA 0020 aerofoil under unsteady flow conditions, using a finite volume flow solver. My question is, if I'm using an unsteady inflow boundary condition upstream of the foil what should the outflow boundary condition be set as. Is a constant pressure outflow boundary condition valid, if placed far enough downstream?

Regards James

Alex March 5, 2001 12:58

Re: Unsteady boundary conditions
It depends on Mach number. If the problem is subsonic then constatnt pressure at outflow boundary will be Ok. If M> 1 then you should set smooth condition d/dn = 0.

clifford bradford March 5, 2001 14:54

Re: Unsteady boundary conditions
Search for Kevin Thompsons paper called "Unsteady boundary Conditions for Hyperbolic systems" in J. Comp. Physics

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