Reply To: applying the force into Fluid in the openLB code not DEFINITION
Dear Massload,
the boundary conditions are applied depending on being a local or non-local operation (e.g., the interpolatedVelocityboundary is non-local as it requires interpolation from neighboring cells) at different stages during collideAndStream() managed by STAGE (e.g., PreCollide(), PostCollide(), etc.).
When you look into src/boundary/setInterpolatedVelocityBoundary3D.hh, the used dynamics and postprocessors (for the local and non-local operations respectively) are listed depending on the alignment of the boundary. In the definitions of the applied dynamics and post-processors, you can find the actually applied boundary treatments. At this point, I kindly recommend you to refer to our User-Guide Chap. 2 about core concepts of OpenLB.