Make Adami loop flipping optimization optional

docs/src/systems/boundary.md

@@ -55,24 +55,28 @@ of the boundary particle ``b``.
 
 ### Hydrodynamic density of dummy particles
 
-We provide five options to compute the boundary density and pressure, determined by the `density_calculator`:
+We provide six options to compute the boundary density and pressure, determined by the `density_calculator`:
 1. (Recommended) With [`AdamiPressureExtrapolation`](@ref), the pressure is extrapolated from the pressure of the
  fluid according to (Adami et al., 2012), and the density is obtained by applying the inverse of the state equation.
  This option usually yields the best results of the options listed here.
-2. With [`SummationDensity`](@ref), the density is calculated by summation over the neighboring particles,
+2. (Only relevant for FSI) With `BernoulliPressureExtrapolation`, the pressure is extrapolated from the 
+ pressure similar to the [`AdamiPressureExtrapolation`](@ref), but a relative velocity dependent pressure part
+ is calculated between moving solids and fluids, which increases the boundary pressure in areas prone to 
+ penetrations.
+3. With [`SummationDensity`](@ref), the density is calculated by summation over the neighboring particles,
  and the pressure is computed from the density with the state equation.
-3. With [`ContinuityDensity`](@ref), the density is integrated from the continuity equation,
+4. With [`ContinuityDensity`](@ref), the density is integrated from the continuity equation,
  and the pressure is computed from the density with the state equation.
  Note that this causes a gap between fluid and boundary where the boundary is initialized
  without any contact to the fluid. This is due to overestimation of the boundary density
  as soon as the fluid comes in contact with boundary particles that initially did not have
  contact to the fluid.
  Therefore, in dam break simulations, there is a visible "step", even though the boundary is supposed to be flat.
  See also [dual.sphysics.org/faq/#Q_13](https://dual.sphysics.org/faq/#Q_13).
-4. With [`PressureZeroing`](@ref), the density is set to the reference density and the pressure
+5. With [`PressureZeroing`](@ref), the density is set to the reference density and the pressure
  is computed from the density with the state equation.
  This option is not recommended. The other options yield significantly better results.
-5. With [`PressureMirroring`](@ref), the density is set to the reference density. The pressure
+6. With [`PressureMirroring`](@ref), the density is set to the reference density. The pressure
  is not used. Instead, the fluid pressure is mirrored as boundary pressure in the
  momentum equation.
  This option is not recommended due to stability issues. See [`PressureMirroring`](@ref)
@@ -93,7 +97,12 @@ where the sum is over all fluid particles, ``\rho_f`` and ``p_f`` denote the den
  AdamiPressureExtrapolation
 ```
 
-#### 4. [`PressureZeroing`](@ref)
+#### 2. [`BernoulliPressureExtrapolation`](@ref)
+```@docs
+ BernoulliPressureExtrapolation
+```
+
+#### 5. [`PressureZeroing`](@ref)
 
 This is the simplest way to implement dummy boundary particles.
 The density of each particle is set to the reference density and the pressure to the
@@ -102,7 +111,7 @@ reference pressure (the corresponding pressure to the reference density by the s
  PressureZeroing
 ```
 
-#### 5. [`PressureMirroring`](@ref)
+#### 6. [`PressureMirroring`](@ref)
 
 Instead of calculating density and pressure for each boundary particle, we modify the
 momentum equation,

examples/fsi/falling_spheres_2d.jl

@@ -63,7 +63,7 @@ fluid_system = WeaklyCompressibleSPHSystem(tank.fluid, fluid_density_calculator,
 
 # ==========================================================================================
 # ==== Boundary
-boundary_density_calculator = AdamiPressureExtrapolation()
+boundary_density_calculator = BernoulliPressureExtrapolation()
 boundary_model = BoundaryModelDummyParticles(tank.boundary.density, tank.boundary.mass,
  state_equation=state_equation,
  boundary_density_calculator,

src/TrixiParticles.jl

@@ -65,7 +65,8 @@ export ArtificialViscosityMonaghan, ViscosityAdami, ViscosityMorris
 export DensityDiffusion, DensityDiffusionMolteniColagrossi, DensityDiffusionFerrari,
  DensityDiffusionAntuono
 export BoundaryModelMonaghanKajtar, BoundaryModelDummyParticles, AdamiPressureExtrapolation,
- PressureMirroring, PressureZeroing, BoundaryModelLastiwka
+ PressureMirroring, PressureZeroing, BoundaryModelLastiwka, BernoulliPressureExtrapolation
+
 export BoundaryMovement
 export examples_dir, validation_dir, trixi_include
 export trixi2vtk