is specified.
The boundary face velocity is extrapolated from the interior using reconstruction gradients. In the case of the Segregated Flow model, an option exists to use only the normal component of the velocity for inflow. This option can stabilize the solution in certain situations.
For subsonic outflow, the boundary pressure is specified.
For supersonic outflow, the boundary face pressure is extrapolated from the adjacent cell value using reconstruction gradients.
When inflow occurs, the boundary static pressure 
is assumed to be given by:
| (124) |
where 
is the normal component of the boundary inflow velocity.
For radial equilibrium outflow, the radial pressure gradient exactly balances the centrifugal forces due to rotation. To apply radial equilibrium to a specified pressure boundary condition, one must impose the condition:
| (125) |
where the subscript i refers to the inner location (that is, the hub in a turbomachine) and 
is the tangential component of the velocity.
To obtain the function 
as a function of r only, the data is sorted into bins. An arbitrary number of 100 bins is chosen. If any bins are empty, they are filled by linear interpolation. Since the interpolated data is going to be numerically integrated, the interpolation order is not very important.
For outflow, the boundary face temperature is extrapolated from the adjacent cell using reconstruction gradients. For inflow, the specified static temperature is used.