[Fix] Interpolation Bounce back

The interpolation bounce back boundary condition was wrongly implemented because the equilibrium calculation was done by looking at the 'deviation_only' property of the lb method equilibrium. However, here we need to apply the equilibrium on the PDF values and not on moments etc.

tests/test_interpolation_boundaries.py

@@ -49,6 +49,9 @@ def couette_flow(stencil, method_enum, zero_centered, wall_distance, compressibl
     lb_step_bouzidi = LatticeBoltzmannStep(domain_size=domain_size, periodicity=periodicity,
                                            lbm_config=lbm_config, compute_velocity_in_every_step=True)
 
+    lb_step_quadratic_bb = LatticeBoltzmannStep(domain_size=domain_size, periodicity=periodicity,
+                                                lbm_config=lbm_config, compute_velocity_in_every_step=True)
+
     def init_wall_distance(boundary_data, **_):
         for cell in boundary_data.index_array:
             cell['q'] = wall_distance
@@ -64,30 +67,23 @@ def couette_flow(stencil, method_enum, zero_centered, wall_distance, compressibl
     lb_step_bouzidi.boundary_handling.set_boundary(bouzidi, slice_from_direction('S', dim))
     lb_step_bouzidi.boundary_handling.set_boundary(moving_wall, slice_from_direction('N', dim))
 
+    lb_step_quadratic_bb.boundary_handling.set_boundary(quadratic_bb, slice_from_direction('S', dim))
+    lb_step_quadratic_bb.boundary_handling.set_boundary(moving_wall, slice_from_direction('N', dim))
+
     lb_step_noslip.run(timesteps)
     lb_step_bouzidi.run(timesteps)
+    lb_step_quadratic_bb.run(timesteps)
 
     if dim == 2:
         noslip_velocity = lb_step_noslip.velocity[domain_size[0] // 2, :, 0]
         bouzidi_velocity = lb_step_bouzidi.velocity[domain_size[0] // 2, :, 0]
+        quadratic_bb_velocity = lb_step_quadratic_bb.velocity[domain_size[0] // 2, :, 0]
     else:
         noslip_velocity = lb_step_noslip.velocity[domain_size[0] // 2, :, domain_size[2] // 2, 0]
         bouzidi_velocity = lb_step_bouzidi.velocity[domain_size[0] // 2, :, domain_size[2] // 2, 0]
-
-    check_velocity(noslip_velocity, bouzidi_velocity, wall_distance)
-
-    lb_step_quadratic_bb = LatticeBoltzmannStep(domain_size=domain_size, periodicity=(True, False),
-                                                lbm_config=lbm_config, compute_velocity_in_every_step=True)
-
-    lb_step_quadratic_bb.boundary_handling.set_boundary(quadratic_bb, slice_from_direction('S', dim))
-    lb_step_quadratic_bb.boundary_handling.set_boundary(moving_wall, slice_from_direction('N', dim))
-    lb_step_quadratic_bb.run(timesteps)
-
-    if dim == 2:
-        quadratic_bb_velocity = lb_step_quadratic_bb.velocity[domain_size[0] // 2, :, 0]
-    else:
         quadratic_bb_velocity = lb_step_quadratic_bb.velocity[domain_size[0] // 2, :, domain_size[2] // 2, 0]
 
+    check_velocity(noslip_velocity, bouzidi_velocity, wall_distance)
     check_velocity(noslip_velocity, quadratic_bb_velocity, wall_distance)