Reply To: Pressure in openLB
thank you for your post.
Please note that, by construction, the physical pressure is assumed to be absolute.
Wrt your questions:
(1) To set a specific pressure value at the boundary, input the desired physical value (e.g. named pF) to the functor which sets the boundary values. So, irrespective of your actual boundary condition (e.g. setLocalPressureBoundary, setInterpolatedPressureBoundary), you can use the following:
AnalyticalConst3D<T,T> rho(converter.getLatticeDensityFromPhysPressure(pF)); // to convert physical pressure to lattice density
sLattice.defineRho(superGeometry, 4, rhoF); // to set the actual value, assuming that your outflow boundary has e.g. material number 4.
2) Unfortunately, we do not have this kind of boundary included in OpenLB out of the box.