Flow Boundaries
Flow boundary components are attached to ends of flow channel components to provide boundary conditions.
Usage
A flow boundary component connects to a flow channel end using the input
parameter. The value of this parameter corresponds to the boundary name corresponding to a specific end of a flow channel. The format for the input
parameter is flow_channel_name:in
or flow_channel_name:out
, where flow_channel_name
is the name of the connected flow channel, and in
or out
depends on which end is being connected. The in
side denotes the "starting" side of the flow channel, which resides at the location specified by the flow channel's position
parameter, and the out
side is the opposite end.
Formulation
Flow boundary formulations differ based on how the boundary flux is computed.
Direct Flux Computation
In this case, the boundary flux is computed directly from the continuous flux function using some solution vector , which is determined by the boundary condition and is in general a combination of the interior solution and exterior boundary data:
Ghost Cell Flux Computation
In this case, the boundary flux is computed using a ghost cell approach. That is, the flux corresponding to the boundary is computed using a numerical flux function , taking the interior solution and ghost cell solution as inputs: in this case for the "right" boundary of the flow channel.
Each boundary condition is defined by its definition of and in general is formed by taking some values from the interior solution and some from external data.