Although the boundary conditions are already defined in the layout.md file, it is not possible to define a particular value to the state variable on a boundary face.
In order to defined a fixed value at the boundary face you can use the boundary condition file. Once layout.md
file is defined, the boundary condition file can be created using following command in the system/mesh/layout/
directory:
$. compile.sh generate_bc.cpp $./a.out
For each block a separate boundary condition files is written in system/mesh/bc/
. The sample boundary condition is as follows:
BOUNDARY CONDITIONS CONFIGURATION ================================= # imn - INTERFACE # imx - COPY_DENSITY - COPY_X_SPEED - COPY_Y_SPEED - COPY_Z_SPEED - FIX_PRESSURE # jmn - COPY_DENSITY - COPY_PRESSURE - NO_SLIP - WALL_TEMPERATURE # jmx - INTERFACE # kmn - COPY_DENSITY - COPY_PRESSURE - FLOW_TANGENCY # kmx - COPY_DENSITY - COPY_PRESSURE - FLOW_TANGENCY FIN
In order to fix the value of a particular variable, depending on the boundary condition type, just input the value in front of Fix_var
line. For example, at imx
boundary, the back pressure is fixed to 101325 Pa. So the boundary condition file is change to :
BOUNDARY CONDITIONS CONFIGURATION ================================= # imn - INTERFACE # imx - COPY_DENSITY - COPY_X_SPEED - COPY_Y_SPEED - COPY_Z_SPEED - FIX_PRESSURE 101325 # jmn - COPY_DENSITY - COPY_PRESSURE - NO_SLIP - WALL_TEMPERATURE # jmx - INTERFACE # kmn - COPY_DENSITY - COPY_PRESSURE - FLOW_TANGENCY # kmx - COPY_DENSITY - COPY_PRESSURE - FLOW_TANGENCY FIN
Input value only in SI units.