## 2.7. Wall

Walls are solid (impermeable) boundaries to fluid flow. Walls allow the permeation of heat and Additional Variables into and out of the domain through the setting of flux and fixed value conditions at wall boundaries.

Walls are the default boundary condition in CFX-Pre for fluid-world and solid-world regions; any of these regions that are not part of an existing boundary condition will remain in a default wall boundary when the CFX-Solver input file is written. For details, see Default Boundary Condition in the CFX-Pre User's Guide.

The treatment of wall boundary conditions for turbulent flow is the same as for laminar flow, except for no-slip conditions. For details, see Wall Function in the CFX-Pre User's Guide.

Information on setting boundary conditions at walls in CFX-Pre is available in Boundary Details: Wall in the CFX-Pre User's Guide.

Additional mathematical information on the wall boundary condition is available in Wall in the CFX-Solver Theory Guide.

Additional information on wall boundaries in multiphase flow is available in Wall Boundaries in Multiphase.

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