Cleanup examples

examples/fluid/accelerated_tank_2d.jl

@@ -4,63 +4,17 @@
 using TrixiParticles
 using OrdinaryDiffEq
 
-# ==========================================================================================
-# ==== Resolution
+# Resolution
 fluid_particle_spacing = 0.05
 
-# Make sure that the kernel support of fluid particles at a boundary is always fully sampled
-boundary_layers = 3
-
-# ==========================================================================================
-# ==== Experiment Setup
-tspan = (0.0, 1.0)
-
-# Boundary geometry and initial fluid particle positions
-initial_fluid_size = (1.0, 0.9)
-tank_size = (1.0, 1.0)
-
-fluid_density = 1000.0
-sound_speed = 10.0
-state_equation = StateEquationCole(; sound_speed, reference_density=fluid_density,
-                                   exponent=7, clip_negative_pressure=false)
-
-tank = RectangularTank(fluid_particle_spacing, initial_fluid_size, tank_size, fluid_density,
-                       acceleration=(0.0, -9.81), state_equation=state_equation,
-                       n_layers=boundary_layers, spacing_ratio=1.0)
-
 # Function for moving boundaries
 movement_function(t) = SVector(0.0, 0.5 * 9.81 * t^2)
 
 is_moving(t) = true
 
 boundary_movement = BoundaryMovement(movement_function, is_moving)
 
-# Import the setup from `hydrostatic_water_column_2d.jl`
 trixi_include(@__MODULE__,
               joinpath(examples_dir(), "fluid", "hydrostatic_water_column_2d.jl"),
               fluid_particle_spacing=fluid_particle_spacing, movement=boundary_movement,
-              acceleration=(0.0, 0.0), tank=tank, semi=nothing, ode=nothing,
-              sol=nothing) # Overwrite `sol` assignment to skip time integration
-
-# ==========================================================================================
-# ==== Simulation
-semi = Semidiscretization(fluid_system, boundary_system)
-ode = semidiscretize(semi, tspan)
-
-info_callback = InfoCallback(interval=50)
-saving_callback = SolutionSavingCallback(dt=0.02, prefix="")
-
-callbacks = CallbackSet(info_callback, saving_callback)
-
-# Use a Runge-Kutta method with automatic (error based) time step size control.
-# Limiting of the maximum stepsize is necessary to prevent crashing.
-# When particles are approaching a wall in a uniform way, they can be advanced
-# with large time steps. Close to the wall, the stepsize has to be reduced drastically.
-# Sometimes, the method fails to do so because forces become extremely large when
-# fluid particles are very close to boundary particles, and the time integration method
-# interprets this as an instability.
-sol = solve(ode, RDPK3SpFSAL35(),
-            abstol=1e-5, # Default abstol is 1e-6 (may need to be tuned to prevent boundary penetration)
-            reltol=1e-3, # Default reltol is 1e-3 (may need to be tuned to prevent boundary penetration)
-            dtmax=1e-2, # Limit stepsize to prevent crashing
-            save_everystep=false, callback=callbacks);
+              tspan=(0.0, 1.0), system_acceleration=(0.0, 0.0))

examples/fluid/hydrostatic_water_column_2d.jl

@@ -23,21 +23,25 @@ state_equation = StateEquationCole(; sound_speed, reference_density=fluid_densit
                                    exponent=7, clip_negative_pressure=false)
 
 tank = RectangularTank(fluid_particle_spacing, initial_fluid_size, tank_size, fluid_density,
-                       n_layers=boundary_layers,
-                       acceleration=(0.0, -gravity), state_equation=state_equation)
+                       n_layers=boundary_layers, acceleration=(0.0, -gravity),
+                       state_equation=state_equation)
 
 # ==========================================================================================
 # ==== Fluid
 smoothing_length = 1.2 * fluid_particle_spacing
 smoothing_kernel = SchoenbergCubicSplineKernel{2}()
 
-viscosity = ArtificialViscosityMonaghan(alpha=0.02, beta=0.0)
+alpha = 0.02
+viscosity = ArtificialViscosityMonaghan(alpha=alpha, beta=0.0)
 
 fluid_density_calculator = ContinuityDensity()
+
+# This is to set acceleration with `trixi_include`
+system_acceleration = (0.0, -gravity)
 fluid_system = WeaklyCompressibleSPHSystem(tank.fluid, fluid_density_calculator,
                                            state_equation, smoothing_kernel,
                                            smoothing_length, viscosity=viscosity,
-                                           acceleration=(0.0, -gravity),
+                                           acceleration=system_acceleration,
                                            source_terms=nothing)
 
 # ==========================================================================================

src/general/semidiscretization.jl

@@ -715,19 +715,27 @@ function update_nhs!(neighborhood_search,
             points_moving=(true, neighbor.ismoving[]))
 end
 
+# This function is the same as the one below to avoid ambiguous dispatch when using `Union`
 function update_nhs!(neighborhood_search,
-                     system::BoundarySPHSystem,
-                     neighbor::Union{FluidSystem, TotalLagrangianSPHSystem,
-                                     BoundarySPHSystem},
-                     u_system, u_neighbor)
-    # Don't update. This NHS is never used.
-    return neighborhood_search
+                     system::BoundarySPHSystem{<:BoundaryModelDummyParticles},
+                     neighbor::FluidSystem, u_system, u_neighbor)
+    # Depending on the density calculator of the boundary model, this NHS is used for
+    # - kernel summation (`SummationDensity`)
+    # - continuity equation (`ContinuityDensity`)
+    # - pressure extrapolation (`AdamiPressureExtrapolation`)
+    #
+    # Boundary coordinates only change over time when `neighbor.ismoving[]`.
+    # The current coordinates of fluids and solids change over time.
+    update!(neighborhood_search, system,
+            current_coordinates(u_system, system),
+            current_coordinates(u_neighbor, neighbor),
+            points_moving=(system.ismoving[], true))
 end
 
+# This function is the same as the one above to avoid ambiguous dispatch when using `Union`
 function update_nhs!(neighborhood_search,
                      system::BoundarySPHSystem{<:BoundaryModelDummyParticles},
-                     neighbor::Union{FluidSystem, TotalLagrangianSPHSystem},
-                     u_system, u_neighbor)
+                     neighbor::TotalLagrangianSPHSystem, u_system, u_neighbor)
     # Depending on the density calculator of the boundary model, this NHS is used for
     # - kernel summation (`SummationDensity`)
     # - continuity equation (`ContinuityDensity`)
@@ -773,6 +781,14 @@ function update_nhs!(neighborhood_search,
             points_moving=(true, false))
 end
 
+function update_nhs!(neighborhood_search,
+                     system::BoundarySPHSystem,
+                     neighbor::FluidSystem,
+                     u_system, u_neighbor)
+    # Don't update. This NHS is never used.
+    return neighborhood_search
+end
+
 function update_nhs!(neighborhood_search,
                      system::BoundaryDEMSystem,
                      neighbor::Union{DEMSystem, BoundaryDEMSystem},