Injection from EB: do not create particles outside of user-specified …

…bounds (#5521)

When using the injection from embedded boundaries along with `zmin`,
`zmax`, `xmin`, `xmax`, etc., we were creating a large number of
macroparticles along the EB surface, and then removing the particles
that are outside of `zmin`, `zmax`, `xmin`, `xmax`, etc. by setting
their ID to an invalid value.

In case where the area defined by `zmin`, `zmax`, `xmin`, `xmax`, etc.
is a small fraction of the EB surface, it is much more efficient not to
create these particles in the first place. In addition, it avoids having
to create a large number of particle IDs, which are eventually not used
in the simulation. (In some use cases, this unnecessarily lead to a
particle ID overflow, i.e. WarpX ended up having to generate particle
IDs that were outside the maximum possible range given by the number of
bits.)

This PR removes this issue.

Source/Particles/PhysicalParticleContainer.cpp

@@ -1483,17 +1483,14 @@ PhysicalParticleContainer::AddPlasmaFlux (PlasmaInjector const& plasma_injector,
                 if (eb_flag_arr(i,j,k).isRegular() || eb_flag_arr(i,j,k).isCovered()) { return; }
                 // Scale by the (normalized) area of the EB surface in this cell
                 num_ppc_real_in_this_cell *= eb_bnd_area_arr(i,j,k);
-            } else
+            }
 #else
             amrex::Real const num_ppc_real_in_this_cell = num_ppc_real; // user input: number of macroparticles per cell
 #endif
-            {
-                // Injection from a plane
-                auto lo = getCellCoords(overlap_corner, dx, {0._rt, 0._rt, 0._rt}, iv);
-                auto hi = getCellCoords(overlap_corner, dx, {1._rt, 1._rt, 1._rt}, iv);
-                // Skip cells that do not overlap with the plane
-                if (!flux_pos->overlapsWith(lo, hi)) { return; }
-            }
+            // Skip cells that do not overlap with the bounds specified by the user (xmin/xmax, ymin/ymax, zmin/zmax)
+            auto lo = getCellCoords(overlap_corner, dx, {0._rt, 0._rt, 0._rt}, iv);
+            auto hi = getCellCoords(overlap_corner, dx, {1._rt, 1._rt, 1._rt}, iv);
+            if (!flux_pos->overlapsWith(lo, hi)) { return; }
 
             auto index = overlap_box.index(iv);
             // Take into account refined injection region