The available Boundary condition options for an inlet are Velocity and Pressure. After selecting a Boundary Condition from the list, a section with the same or a similar name displays underneath. For example, if Velocity is selected, a Velocity section, where further settings are defined, is displayed.
The Normal inflow velocity is specified as u = −nU0, where n is the boundary normal pointing out of the domain and U0 is the normal inflow speed.
The Velocity field option sets the velocity vector to u = u0. The components of the inlet velocity vector u0 should be defined for this choice.
This option specifies the normal stress, which in most cases is approximately equal to the pressure. If the reference pressure pref, defined at the physics interface level, is equal to 0, the value of the Pressure p0, at the boundary, is the absolute pressure. Otherwise, p0 is the relative pressure at the boundary.
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The Suppress backflow option adjusts the inlet pressure locally in order to prevent fluid from exiting the domain through the boundary. If suppress backflow is deselected, the inlet boundary can become an outlet depending on the pressure field in the rest of the domain.
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Flow direction controls in which direction the fluid enters the domain.
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For Normal flow, it prescribes zero tangential velocity component.
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For User defined, an Inflow velocity direction du (dimensionless) should be specified. The magnitude of du does not matter, only the direction. du must point into the domain.
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