CFD Online Discussion Forums - No flow rate in outlet with advective velocity

Hello,

I am working in a project with rhoCentralFoam. It is transonic-supersonic flow with two inlets and one outlet. In order to avoid wave reflections, I have defined the boundary condition for pressure in outlet as waveTransmissive. The problem is that if a define the velocity as advective, I get no flow rate in outlet. Velocity is zero. I know that it should be the normal behaviour when there is a backflow (negative flux), but I dont know why it should be so. Inside the domain the pressure is higher than atmosphere, and in the waveTrasmissive the fieldInf is defined as 1 atm. I have no clue what can be the problem.

The definition in oultet for pressure:

Quote:

type waveTransmissive;
value uniform 101300; //important for correct I/O
field p; //the name of the field that we are working on
gamma 1.4; //the ratio of specific heats
phi phi; //the name of the volumetric flux field ( or if you use the mass flux phi, it will be divided by rho)
rho rho; //the name of the density field
psi thermo:psi; //the name of the field that is the deriv. of density with respect to pressure
lInf 10; //a measure of how far away the far-field condition should be
fieldInf 101300; //the far-field value to be applied to p

and for velocity:

Quote:

type advective;
phi phi;

With this definition, the behaviour is like a wall.

If I put inletOutlet for velocity in outlet, it seems to work fine.

With best regards
Robert