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.

https://github.com/user-attachments/assets/dadcc794-bcdc-4f9b-a3c2-3d7e2228b8ea

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

https://github.com/user-attachments/assets/ff53b939-ff8f-49d9-b515-576b112ad28e

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 15.95745% with 79 lines in your changes missing coverage. Please review.

Project coverage is 69.62%. Comparing base (3cb59d4) to head (99b583f).

Files with missing lines	Patch %	Lines
src/schemes/boundary/open_boundary/system.jl	8.16%	45 Missing :warning:
...c/schemes/boundary/open_boundary/boundary_zones.jl	32.00%	17 Missing :warning:
src/callbacks/particle_shifting.jl	0.00%	14 Missing :warning:
src/callbacks/update.jl	0.00%	2 Missing :warning:
src/schemes/boundary/open_boundary/mirroring.jl	50.00%	1 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #827      +/-   ##
==========================================
- Coverage   70.25%   69.62%   -0.64%     
==========================================
  Files         106      106              
  Lines        6906     6979      +73     
==========================================
+ Hits         4852     4859       +7     
- Misses       2054     2120      +66     

Flag	Coverage Δ
unit	69.62% <15.95%> (-0.64%)	:arrow_down:

Flags with carried forward coverage won't be shown. Click here to find out more.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

:rocket: New features to boost your workflow:

• :snowflake: Test Analytics: Detect flaky tests, report on failures, and find test suite problems.