Add shifting zone

[LasNikas]

In this PR, I aimed to further improve the robustness of the open boundary implementation. To test this, I simulated a pulse wave propagation scenario with prescribed_pressure_in = 1000 and prescribed_pressure_out = 0 (see code below).

To provoke instability, I initially removed a row of buffer particles (shown in red). The fluid particles (blue) in both simulations are evolved using EDAC without any particle shifting (i.e., no ParticleShiftingCallback).

In the top animation, I introduced a shifting zone (black frame) specifically for the inflow boundary zone, where the PST is applied exclusively within this region. This shifting zone is independent of the global ParticleShiftingCallback and can be enabled or disabled for each boundary zone as needed.

shifted_buffer_zone.mp4

using TrixiParticles

trixi_include(@__MODULE__, joinpath(examples_dir(), "fluid", "pipe_flow_2d.jl");
              open_boundary_layers=14, sol=nothing)

patch = RectangularShape(particle_spacing, (1, pipe.n_particles_per_dimension[2]),
                         (-0.6, 0.0), density=fluid_density)
ic = setdiff(extrude_geometry(plane_in; particle_spacing, density=fluid_density,
                              direction=-flow_direction, n_extrude=open_boundary_layers),
             patch)

# With shifting zone
inflow_shifted = BoundaryZone(; plane=([0.0, 0.0], [0.0, domain_size[2]]),
                              plane_normal=flow_direction, open_boundary_layers,
                              density=fluid_density, particle_spacing, initial_condition=ic,
                              shift_particles=true, boundary_type=InFlow(),
                              boundary_coordinates=pipe.boundary.coordinates)

trixi_include(@__MODULE__, joinpath(examples_dir(), "fluid", "pipe_flow_2d.jl");
              open_boundary_layers=14, domain_size=(2.0, 0.4), tspan=(0.0, 5.0),
              prefix="shifted", open_boundary_model=BoundaryModelTafuni(),
              inflow=inflow_shifted,
              reference_velocity_in=nothing, reference_density_in=nothing,
              reference_velocity_out=nothing, reference_density_out=nothing,
              reference_pressure_in=1000, reference_pressure_out=0)

# Whithout shifting zone
inflow = BoundaryZone(; plane=([0.0, 0.0], [0.0, domain_size[2]]),
                      plane_normal=flow_direction, open_boundary_layers,
                      density=fluid_density, particle_spacing, initial_condition=ic,
                      boundary_type=InFlow())

trixi_include(@__MODULE__, joinpath(examples_dir(), "fluid", "pipe_flow_2d.jl");
              open_boundary_layers=14, domain_size=(2.0, 0.4), tspan=(0.0, 5.0),
              prefix="", open_boundary_model=BoundaryModelTafuni(), inflow=inflow,
              reference_velocity_in=nothing, reference_density_in=nothing,
              reference_velocity_out=nothing, reference_density_out=nothing,
              reference_pressure_in=1000, reference_pressure_out=0)

Same setup with higher resolution and with pressure_in = 5000 and pressure_out = 0 and without any artificial provocation of instability

pulse_wave_propagation.mp4

[codecov]

Codecov Report

Attention: Patch coverage is 14.58333% with 82 lines in your changes missing coverage. Please review.

Project coverage is 69.91%. Comparing base (114a57b) to head (2c21cec).

Files with missing lines	Patch %	Lines
src/schemes/boundary/open_boundary/system.jl	8.00%	46 Missing ⚠️
...c/schemes/boundary/open_boundary/boundary_zones.jl	29.62%	19 Missing ⚠️
src/callbacks/particle_shifting.jl	0.00%	14 Missing ⚠️
src/callbacks/update.jl	0.00%	2 Missing ⚠️
src/schemes/boundary/open_boundary/mirroring.jl	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #827      +/-   ##
==========================================
- Coverage   70.60%   69.91%   -0.69%     
==========================================
  Files         106      106              
  Lines        6769     6845      +76     
==========================================
+ Hits         4779     4786       +7     
- Misses       1990     2059      +69     

Flag	Coverage Δ
unit	69.91% <14.58%> (-0.69%)	⬇️

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