An inlet boundary condition is used where the flow is predominantly directed into the domain. The boundary condition can be set in a number of ways depending on how you want to specify the conditions, and what particular physical models you are using for the simulation.
There are many different types of inlet boundary condition combinations for the mass and momentum equations. For all other transport equations, the value is specified directly at the inlet, or specified in terms of a simple relationship that constrains the dependent variable.
Important: If you accidentally set the velocity at an inlet to be flowing out of the domain, the inlet will behave as an outlet: wall building will not be turned on.
Information on setting Inlet values using CFX-Pre is available. For details, see Boundary Details: Inlet in the CFX-Pre User's Guide.
Information on the mathematical implementation of the inlet boundary condition is available.