This data setup are used to define the outflow condition features. The outflow geometry is restricted to rectangular/line forms in 3D/2D configuration. In the particular case of cylindrical geometries, the outlets can be circular, annular or bowed rectangular. In fact, the geometry of the outlet fits the grid topology.
&Outlet_Boundary_Conditions
Type_of_BC= "OUTLET", Direction_Normal_Plan= 1 ,
Plan_Location_Coordinate= -0.05 ,
Start_Coordinate_of_First_Span = -0.01, End_Coordinate_of_First_Span = 0.01,
Start_Coordinate_of_Second_Span= 0.0 , End_Coordinate_of_Second_Span= 0.0 ,
Pressure_Reference_Value = 0.0 , Length_Scale = 1.0 ,
Flow_Direction= 1 ,
End_of_Data_Block= .true. /
Whatever the grid topology, the orientation and the span of the outflow are defined by means of :
the normal vector of the outlet plane associated to a specific direction (I,J or K).
the coordinates associated to the position of the outlet sides along the two perpendicular directions to the normal vector (denoted the first and second span directions).
When the normal vector is oriented along the I-direction, the first span direction is J and the second is K.
When the the normal vector is oriented along the J-direction, the first span direction is I and the second is K.
When the the normal vector is oriented along the K-direction, the first span direction is I and the second is J.
By default the domain is enclosed. The boundary conditions defined by default at the ends of the domain are walls. When an outlet is placed at the end of the domain, it replaces the wall conditions over the outflow area.
Don't forget to set the boolean data “End_of_Data_Block” at the end of the namelist. A “.true.” value means the end of the data block when several namelists are used to create several outlets.
Find some examples here about outflow configurations.