Refactor neighborhood search and update functions for improved clarity and performance.

Reduce the branch to only the split-integration/update-system refactor that is still unique on top of upstream/main.

Author: svchb

src/callbacks/split_integration.jl

@@ -214,46 +214,14 @@ end
 
 # Update the systems before calling `interact!` to compute forces
 function update_systems_split!(semi, v_ode, u_ode, t)
-    # First update step before updating the NHS
-    # (for example for writing the current coordinates in the solid system)
-    foreach_system(semi) do system
-        v = wrap_v(v_ode, system, semi)
-        u = wrap_u(u_ode, system, semi)
-
-        update_positions!(system, v, u, v_ode, u_ode, semi, t)
-    end
-
-    # Second update step.
-    # This is used to calculate density and pressure of the fluid systems
-    # before updating the boundary systems,
-    # since the fluid pressure is needed by the Adami interpolation.
-    foreach_system(semi) do system
-        v = wrap_v(v_ode, system, semi)
-        u = wrap_u(u_ode, system, semi)
-
-        update_quantities!(system, v, u, v_ode, u_ode, semi, t)
-    end
-
-    # Perform correction and pressure calculation
-    foreach_system(semi) do system
-        v = wrap_v(v_ode, system, semi)
-        u = wrap_u(u_ode, system, semi)
-
-        update_pressure!(system, v, u, v_ode, u_ode, semi, t)
-    end
-
     # No `update_boundary_interpolation!` for performance reasons, or we will lose
     # a lot of the speedup that we can gain with split integration.
     # We assume that the TLSPH particles move so little during the substeps
     # that the extrapolated pressure/density values can be treated as constant.
-
-    # Final update step for all remaining systems
-    foreach_system(semi) do system
-        v = wrap_v(v_ode, system, semi)
-        u = wrap_u(u_ode, system, semi)
-
-        update_final!(system, v, u, v_ode, u_ode, semi, t)
-    end
+    return update_systems!(v_ode, u_ode, semi, t;
+                           update_nhs=false,
+                           update_implicit_sph=false,
+                           update_boundary_interpolation=false)
 end
 
 function system_interaction_split!(dv_ode_split, v_ode, u_ode, semi,

src/general/semidiscretization.jl

@@ -469,9 +469,11 @@ function kick!(dv_ode, v_ode, u_ode, semi, t)
     return dv_ode
 end
 
-# Update the systems and neighborhood searches (NHS) for a simulation
-# before calling `interact!` to compute forces.
-function update_systems_and_nhs(v_ode, u_ode, semi, t)
+# Update the systems for a simulation before calling `interact!` to compute forces.
+function update_systems!(v_ode, u_ode, semi, t;
+                         update_nhs=true,
+                         update_implicit_sph=true,
+                         update_boundary_interpolation=true)
     # First update step before updating the NHS
     # (for example for writing the current coordinates in the TLSPH system)
     foreach_system(semi) do system
@@ -481,8 +483,9 @@ function update_systems_and_nhs(v_ode, u_ode, semi, t)
         update_positions!(system, v, u, v_ode, u_ode, semi, t)
     end
 
-    # Update NHS
-    @trixi_timeit timer() "update nhs" update_nhs!(semi, u_ode)
+    if update_nhs
+        @trixi_timeit timer() "update nhs" update_nhs!(semi, u_ode)
+    end
 
     # Second update step.
     # This is used to calculate density and pressure of the fluid systems
@@ -495,7 +498,9 @@ function update_systems_and_nhs(v_ode, u_ode, semi, t)
         update_quantities!(system, v, u, v_ode, u_ode, semi, t)
     end
 
-    update_implicit_sph!(semi, v_ode, u_ode, t)
+    if update_implicit_sph
+        update_implicit_sph!(semi, v_ode, u_ode, t)
+    end
 
     # Perform correction and pressure calculation
     foreach_system(semi) do system
@@ -507,11 +512,13 @@ function update_systems_and_nhs(v_ode, u_ode, semi, t)
 
     # This update depends on the computed quantities of the fluid system and therefore
     # needs to be after `update_quantities!`.
-    foreach_system(semi) do system
-        v = wrap_v(v_ode, system, semi)
-        u = wrap_u(u_ode, system, semi)
+    if update_boundary_interpolation
+        foreach_system(semi) do system
+            v = wrap_v(v_ode, system, semi)
+            u = wrap_u(u_ode, system, semi)
 
-        update_boundary_interpolation!(system, v, u, v_ode, u_ode, semi, t)
+            update_boundary_interpolation!(system, v, u, v_ode, u_ode, semi, t)
+        end
     end
 
     # Final update step for all remaining systems
@@ -523,6 +530,15 @@ function update_systems_and_nhs(v_ode, u_ode, semi, t)
     end
 end
 
+# Update the systems and neighborhood searches (NHS) for a simulation
+# before calling `interact!` to compute forces.
+function update_systems_and_nhs(v_ode, u_ode, semi, t)
+    return update_systems!(v_ode, u_ode, semi, t;
+                           update_nhs=true,
+                           update_implicit_sph=true,
+                           update_boundary_interpolation=true)
+end
+
 # The `SplitIntegrationCallback` overwrites `semi_wrap` to use a different
 # semidiscretization for wrapping arrays.
 # TODO `semi` is not used yet, but will be used when the source terms API is modified