make nodal reductions work with distributed multi-volume (example)

Author: majosm

examples/multivolume-mpi.py

@@ -359,19 +359,26 @@ def my_get_timestep(step, t, state):
             wall_dt = actx.to_numpy(
                 nodal_min(
                     discr, dd_vol_wall,
-                    wall_lengthscales**2 * current_cfl/wall_alpha))[()]
+                    wall_lengthscales**2 * current_cfl/wall_alpha,
+                    initial=np.inf))[()]
         else:
             wall_dt = current_dt
         return min(fluid_dt, wall_dt)
 
     def my_write_status(step, t, dt, fluid_state, wall_temperature):
         dv = fluid_state.dv
-        p_min = actx.to_numpy(nodal_min(discr, dd_vol_fluid, dv.pressure))
-        p_max = actx.to_numpy(nodal_max(discr, dd_vol_fluid, dv.pressure))
-        fluid_t_min = actx.to_numpy(nodal_min(discr, dd_vol_fluid, dv.temperature))
-        fluid_t_max = actx.to_numpy(nodal_max(discr, dd_vol_fluid, dv.temperature))
-        wall_t_min = actx.to_numpy(nodal_min(discr, dd_vol_wall, wall_temperature))
-        wall_t_max = actx.to_numpy(nodal_max(discr, dd_vol_wall, wall_temperature))
+        p_min = actx.to_numpy(
+            nodal_min(discr, dd_vol_fluid, dv.pressure, initial=np.inf))
+        p_max = actx.to_numpy(
+            nodal_max(discr, dd_vol_fluid, dv.pressure, initial=0.))
+        fluid_t_min = actx.to_numpy(
+            nodal_min(discr, dd_vol_fluid, dv.temperature, initial=np.inf))
+        fluid_t_max = actx.to_numpy(
+            nodal_max(discr, dd_vol_fluid, dv.temperature, initial=0.))
+        wall_t_min = actx.to_numpy(
+            nodal_min(discr, dd_vol_wall, wall_temperature, initial=np.inf))
+        wall_t_max = actx.to_numpy(
+            nodal_max(discr, dd_vol_wall, wall_temperature, initial=0.))
         if constant_cfl:
             fluid_cfl = current_cfl
             wall_cfl = current_cfl
@@ -380,12 +387,14 @@ def my_write_status(step, t, dt, fluid_state, wall_temperature):
             fluid_cfl = actx.to_numpy(
                 nodal_max(
                     discr, dd_vol_fluid, get_viscous_cfl(
-                        discr, dt, fluid_state, volume_dd=dd_vol_fluid)))
+                        discr, dt, fluid_state, volume_dd=dd_vol_fluid),
+                    initial=0.))
             wall_alpha = wall_time_scale * wall_model.thermal_diffusivity()
             wall_cfl = actx.to_numpy(
                 nodal_max(
                     discr, dd_vol_wall,
-                    wall_alpha * dt/wall_lengthscales**2))
+                    wall_alpha * dt/wall_lengthscales**2,
+                    initial=0.))
         if rank == 0:
             logger.info(f"Step: {step}, T: {t}, DT: {dt}\n"
                         f"----- Fluid CFL: {fluid_cfl}, Wall CFL: {wall_cfl}\n"
@@ -471,8 +480,10 @@ def my_health_check(pressure):
                                      health_pres_min, health_pres_max),
                                      op="lor"):
             health_error = True
-            p_min = actx.to_numpy(nodal_min(discr, dd_vol_fluid, pressure))
-            p_max = actx.to_numpy(nodal_max(discr, dd_vol_fluid, pressure))
+            p_min = actx.to_numpy(
+                nodal_min(discr, dd_vol_fluid, pressure, initial=np.inf))
+            p_max = actx.to_numpy(
+                nodal_max(discr, dd_vol_fluid, pressure, initial=0.))
             logger.info(f"Pressure range violation ({p_min=}, {p_max=})")
         return health_error