#[cfg(feature = "parallel")]
use rayon::prelude::*;
use crate::geometry::ParticlesContacts;
use crate::math::{Real, Vector};
use crate::object::{Boundary, Fluid};
use crate::solver::NonPressureForce;
use crate::TimestepManager;
#[derive(Clone)]
pub struct XSPHViscosity {
pub boundary_viscosity_coefficient: Real,
pub fluid_viscosity_coefficient: Real,
}
impl XSPHViscosity {
pub fn new(fluid_viscosity_coefficient: Real, boundary_viscosity_coefficient: Real) -> Self {
Self {
boundary_viscosity_coefficient,
fluid_viscosity_coefficient,
}
}
}
impl NonPressureForce for XSPHViscosity {
fn solve(
&mut self,
timestep: &TimestepManager,
_kernel_radius: Real,
fluid_fluid_contacts: &ParticlesContacts,
fluid_boundaries_contacts: &ParticlesContacts,
fluid: &mut Fluid,
boundaries: &[Boundary],
densities: &[Real],
) {
let boundary_viscosity_coefficient = self.boundary_viscosity_coefficient;
let fluid_viscosity_coefficient = self.fluid_viscosity_coefficient;
let velocities = &fluid.velocities;
let volumes = &fluid.volumes;
let density0 = fluid.density0;
par_iter_mut!(fluid.accelerations)
.enumerate()
.for_each(|(i, acceleration)| {
let mut added_fluid_vel = Vector::zeros();
let mut added_boundary_vel = Vector::zeros();
let vi = velocities[i];
if self.fluid_viscosity_coefficient != na::zero::<Real>() {
for c in fluid_fluid_contacts
.particle_contacts(i)
.read()
.unwrap()
.iter()
{
if c.i_model == c.j_model {
added_fluid_vel += (velocities[c.j] - vi)
* (fluid_viscosity_coefficient
* c.weight
* volumes[c.j]
* density0
/ densities[c.j]);
}
}
}
if self.boundary_viscosity_coefficient != na::zero::<Real>() {
for c in fluid_boundaries_contacts
.particle_contacts(i)
.read()
.unwrap()
.iter()
{
let delta = (boundaries[c.j_model].velocities[c.j] - vi)
* (boundary_viscosity_coefficient
* c.weight
* boundaries[c.j_model].volumes[c.j]
* density0
/ densities[c.i]);
added_boundary_vel += delta;
let mi = volumes[c.i] * density0;
boundaries[c.j_model].apply_force(c.j, delta * (-mi * timestep.inv_dt()));
}
}
*acceleration +=
added_fluid_vel * timestep.inv_dt() + added_boundary_vel * timestep.inv_dt();
})
}
fn apply_permutation(&mut self, _: &[usize]) {}
}