**** Entered By: akpaul @ 03/28/2005 04:44 PM ****


Q. If I have two boundary conditions at regions next to each other (i.e., sharing an edge) such as an Inlet and Wall, how does the CFX Solver and CFX-Post handle this?

1) For CFX-5, how are both boundary conditions applied to the control volume when they share an edge?
2) For CFX-Post, how is this treated when post-processing "Hybrid" results?


A.
- The flow solver always uses the exact value specified by the user to calculate the flux through the control volume face on a wall or the inlet, when they share an edge. (Similarly for other combination's of BC's).This is because there will be separate control volume faces attached to the wall and inlet for the given node/vertex on the shared edge.

- Hence the control volume value is a function of both the wall value and the inlet value. i.e. both values are applied by the flow solver for the same control volume.

- The "hybrid" value displayed at a node by CFX Post has to be one or the other and hence is not exactly the boundary condition applied by the flow solver (it's one or the other).

Hierarchy for plotting in CFX - POST in such situations for most variables is this (in decreasing order):

Inlet, Fluid Solid Interface, Wall, Opening, Outlet, Interface

Hierarchy for pressure is this:

Outlet, Fluid Solid Interface, Wall, Inlet, Opening, Interface

Hierarchy for wall only values:

Fluid Solid Interface, Wall, all others have same priority


**** Entered By: akpaul @ 03/28/2005 04:44 PM ****


Q. If I have two boundary conditions at regions next to each other (i.e., sharing an edge) such as an Inlet and Wall, how does the CFX Solver and CFX-Post handle this?

1) For CFX-5, how are both boundary conditions applied to the control volume when they share an edge?
2) For CFX-Post, how is this treated when post-processing "Hybrid" results?


A.
- The flow solver always uses the exact value specified by the user to calculate the flux through the control volume face on a wall or the inlet, when they share an edge. (Similarly for other combination's of BC's).This is because there will be separate control volume faces attached to the wall and inlet for the given node/vertex on the shared edge.

- Hence the control volume value is a function of both the wall value and the inlet value. i.e. both values are applied by the flow solver for the same control volume.

- The "hybrid" value displayed at a node by CFX Post has to be one or the other and hence is not exactly the boundary condition applied by the flow solver (it's one or the other).

Hierarchy for plotting in CFX - POST in such situations for most variables is this (in decreasing order):

Inlet, Fluid Solid Interface, Wall, Opening, Outlet, Interface

Hierarchy for pressure is this:

Outlet, Fluid Solid Interface, Wall, Inlet, Opening, Interface

Hierarchy for wall only values:

Fluid Solid Interface, Wall, all others have same priority





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