# Boundary conditions for supersonic flow over a cavity.

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July 5, 2020, 11:07
Boundary conditions for supersonic flow over a cavity.
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Harjit
Join Date: Feb 2020
Posts: 7
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Hello everyone,

I'm modelling a 2D problem involving flow @ M=1.5 over a cavity. First, I'm trying to model the cavity with the same BCs as one reference paper.

So the free stream conditions are P_inf=66.4 kPa, T_inf=218 K and M_inf=1.5 and the boundary conditions are as following (check the figures):

Inlet (A) : the solution of the two-dimensional steady-state Navier-Stokes equations over a flat plate is used as inflow boundary condition to make sure the flow is fully developed at the entrance of the cavity.

Upper wall (H) and Outlet (G) are imposed as pressure-far-field with the free stream conditions.

All the others (B, C, D, E, F) as wall with no slip conditions.

and for the flat plate as follow:

A, D, C as pressure-far-field with free stream conditions; B as wall.

The stready is done and I have similar thickness for the boundary layer. For the transient I did /file/interpolate/read-data and read data from the steady case. The meshs are exactly the same. The density of air is set to ideal-gas.

However, my results for the transient study on the cavity do not make any sense. I have tried also putting the inlet as pressure-far-field but nothing changed. I have attached all the pictures.

Could anyone tell me if I'm doing something wrong?

Attached Images
 bcs.jpg (32.3 KB, 5 views) bcs_p.jpg (28.4 KB, 4 views) bl_v.jpg (45.6 KB, 5 views) open_p.jpg (36.8 KB, 6 views) open_v.jpg (36.8 KB, 4 views)

 Tags boundaries condition, cavity flow, supersonic flow