[AshwaniAssam]

In a general 3D CFD solver how can one calculate the free-stream pressure gradient value at the wall?

I mean, at wall how can we knowthe pressure gradient at the boundary layer formed in the flow.

Any advice in this regard will be very nice.

Thank u.

[FMDenaro]

I am not sure to understand your question (free-stream and wall??).

However, the BL theory say that for very low viscosity value you have dp/dn->0, therefore you can use the pressure external to the BL.

[AshwaniAssam]

Thank u for the reply. Actually I have a boundary condition to implement at the wall which requires pressure gradient at the edge of boundary layer. Now, the question is how do we calculate this value, while applying the wall boundary condition. This value will vary along the wall.

Sorry, for making the question unclear.

[FMDenaro]

Originally Posted by AshwaniAssam

Thank u for the reply. Actually I have a boundary condition to implement at the wall which requires pressure gradient at the edge of boundary layer. Now, the question is how do we calculate this value, while applying the wall boundary condition. This value will vary along the wall.

Sorry, for making the question unclear.

for the "edge of boundary layer" you mean the inviscid region? Do you have already a known solution forthe external field?

[AshwaniAssam]

Yes, we have a known solution. yes by the edge we mean inviscid solution (edge of boundary layer). We are solving explicit scheme, so we know every previous time step all solution.

with regards
Ashwani

[FMDenaro]

Again, for low viscosity value the external pressure field transmits into the boundary layer according to dp/dn=0.

[aerosjc]

If the boundary layer is separated, the pressure gradient is not zero. How to handle such conditions?