SummationByParts/src/euler.rs

590 lines
15 KiB
Rust
Raw Normal View History

2020-01-25 19:40:55 +00:00
use super::operators::{SbpOperator, UpwindOperator};
use super::Grid;
use ndarray::prelude::*;
use ndarray::{azip, Zip};
pub const GAMMA: f32 = 1.4;
#[derive(Clone, Debug)]
/// A 4 x ny x nx array
pub struct Field(pub(crate) Array3<f32>);
impl std::ops::Deref for Field {
type Target = Array3<f32>;
fn deref(&self) -> &Self::Target {
&self.0
}
}
impl std::ops::DerefMut for Field {
fn deref_mut(&mut self) -> &mut Self::Target {
&mut self.0
}
}
impl Field {
pub fn new(ny: usize, nx: usize) -> Self {
let field = Array3::zeros((4, ny, nx));
Self(field)
}
pub fn nx(&self) -> usize {
self.0.shape()[2]
}
pub fn ny(&self) -> usize {
self.0.shape()[1]
}
pub fn rho(&self) -> ArrayView2<f32> {
self.slice(s![0, .., ..])
}
pub fn rhou(&self) -> ArrayView2<f32> {
self.slice(s![1, .., ..])
}
pub fn rhov(&self) -> ArrayView2<f32> {
self.slice(s![2, .., ..])
}
pub fn e(&self) -> ArrayView2<f32> {
self.slice(s![3, .., ..])
}
pub fn rho_mut(&mut self) -> ArrayViewMut2<f32> {
self.slice_mut(s![0, .., ..])
}
pub fn rhou_mut(&mut self) -> ArrayViewMut2<f32> {
self.slice_mut(s![1, .., ..])
}
pub fn rhov_mut(&mut self) -> ArrayViewMut2<f32> {
self.slice_mut(s![2, .., ..])
}
pub fn e_mut(&mut self) -> ArrayViewMut2<f32> {
self.slice_mut(s![3, .., ..])
}
#[allow(unused)]
pub fn components(
&self,
) -> (
ArrayView2<f32>,
ArrayView2<f32>,
ArrayView2<f32>,
ArrayView2<f32>,
) {
(self.rho(), self.rhou(), self.rhov(), self.e())
}
#[allow(unused)]
pub fn components_mut(
&mut self,
) -> (
ArrayViewMut2<f32>,
ArrayViewMut2<f32>,
ArrayViewMut2<f32>,
ArrayViewMut2<f32>,
) {
let mut iter = self.0.outer_iter_mut();
let rho = iter.next().unwrap();
let rhou = iter.next().unwrap();
let rhov = iter.next().unwrap();
let e = iter.next().unwrap();
assert_eq!(iter.next(), None);
(rho, rhou, rhov, e)
}
fn north(&self) -> ArrayView2<f32> {
self.slice(s![.., self.ny() - 1, ..])
}
fn south(&self) -> ArrayView2<f32> {
self.slice(s![.., 0, ..])
}
fn east(&self) -> ArrayView2<f32> {
self.slice(s![.., .., self.nx() - 1])
}
fn west(&self) -> ArrayView2<f32> {
self.slice(s![.., .., 0])
}
fn north_mut(&mut self) -> ArrayViewMut2<f32> {
let ny = self.ny();
self.slice_mut(s![.., ny - 1, ..])
}
fn south_mut(&mut self) -> ArrayViewMut2<f32> {
self.slice_mut(s![.., 0, ..])
}
fn east_mut(&mut self) -> ArrayViewMut2<f32> {
let nx = self.nx();
self.slice_mut(s![.., .., nx - 1])
}
fn west_mut(&mut self) -> ArrayViewMut2<f32> {
self.slice_mut(s![.., .., 0])
}
}
#[allow(unused)]
pub(crate) fn advance_upwind<UO>(
prev: &Field,
fut: &mut Field,
dt: f32,
grid: &Grid<UO>,
work_buffers: Option<&mut WorkBuffers>,
) where
UO: UpwindOperator,
{
assert_eq!(prev.0.shape(), fut.0.shape());
let mut wb: WorkBuffers;
let (y, k, tmp) = if let Some(x) = work_buffers {
(&mut x.y, &mut x.buf, &mut x.tmp)
} else {
wb = WorkBuffers::new(prev.nx(), prev.ny());
(&mut wb.y, &mut wb.buf, &mut wb.tmp)
};
let boundaries = BoundaryTerms {
north: Boundary::This,
south: Boundary::This,
west: Boundary::This,
east: Boundary::This,
};
for i in 0..4 {
// y = y0 + c*kn
y.assign(&prev);
match i {
0 => {}
1 | 2 => {
y.scaled_add(1.0 / 2.0 * dt, &k[i - 1]);
}
3 => {
y.scaled_add(dt, &k[i - 1]);
}
_ => {
unreachable!();
}
};
RHS_upwind(&mut k[i], &y, grid, &boundaries, tmp);
}
Zip::from(&mut fut.0)
.and(&prev.0)
.and(&*k[0])
.and(&*k[1])
.and(&*k[2])
.and(&*k[3])
.apply(|y1, &y0, &k1, &k2, &k3, &k4| *y1 = y0 + dt / 6.0 * (k1 + 2.0 * k2 + 2.0 * k3 + k4));
}
/// Solving (Au)_x + (Bu)_y
/// with:
/// A B
/// [ 0, 0, 0] [ 0, 1, 0]
/// [ 0, 0, -1] [ 1, 0, 0]
/// [ 0, -1, 0] [ 0, 0, 0]
pub(crate) fn advance<SBP>(
prev: &Field,
fut: &mut Field,
dt: f32,
grid: &Grid<SBP>,
work_buffers: Option<&mut WorkBuffers>,
) where
SBP: SbpOperator,
{
assert_eq!(prev.0.shape(), fut.0.shape());
let mut wb: WorkBuffers;
let (y, k, tmp) = if let Some(x) = work_buffers {
(&mut x.y, &mut x.buf, &mut x.tmp)
} else {
wb = WorkBuffers::new(prev.nx(), prev.ny());
(&mut wb.y, &mut wb.buf, &mut wb.tmp)
};
let boundaries = BoundaryTerms {
north: Boundary::This,
south: Boundary::This,
west: Boundary::This,
east: Boundary::This,
};
for i in 0..4 {
// y = y0 + c*kn
y.assign(&prev);
match i {
0 => {}
1 | 2 => {
y.scaled_add(1.0 / 2.0 * dt, &k[i - 1]);
}
3 => {
y.scaled_add(dt, &k[i - 1]);
}
_ => {
unreachable!();
}
};
RHS(&mut k[i], &y, grid, &boundaries, tmp);
}
Zip::from(&mut fut.0)
.and(&prev.0)
.and(&*k[0])
.and(&*k[1])
.and(&*k[2])
.and(&*k[3])
.apply(|y1, &y0, &k1, &k2, &k3, &k4| *y1 = y0 + dt / 6.0 * (k1 + 2.0 * k2 + 2.0 * k3 + k4));
}
fn pressure(gamma: f32, rho: f32, rhou: f32, rhov: f32, e: f32) -> f32 {
(gamma - 1.0) * (e - (rhou * rhou + rhov * rhov) / (2.0 * rho))
}
#[allow(non_snake_case)]
/// This flux is rotated by the grid metrics
/// (Au)_x + (Bu)_y = 1/J [
/// (J xi_x Au)_xi + (J eta_x Au)_eta
/// (J xi_y Bu)_xi + (J eta_y Bu)_eta
/// ]
/// where J is the grid determinant
///
/// This is used both in fluxes and SAT terms
fn RHS<SBP: SbpOperator>(
k: &mut Field,
y: &Field,
grid: &Grid<SBP>,
boundaries: &BoundaryTerms,
tmp: &mut (Field, Field, Field, Field),
) {
let ehat = &mut tmp.0;
let fhat = &mut tmp.1;
fluxes([ehat, fhat], y, grid);
let de = &mut tmp.2;
let df = &mut tmp.3;
SBP::diffxi(ehat.rho(), de.rho_mut());
SBP::diffxi(ehat.rhou(), de.rhou_mut());
SBP::diffxi(ehat.rhov(), de.rhov_mut());
SBP::diffxi(ehat.e(), de.e_mut());
SBP::diffeta(fhat.rho(), df.rho_mut());
SBP::diffeta(fhat.rhou(), df.rhou_mut());
SBP::diffeta(fhat.rhov(), df.rhov_mut());
SBP::diffeta(fhat.e(), df.e_mut());
// And dissipation...
ndarray::azip!((out in &mut k.0,
eflux in &de.0,
fflux in &df.0,
detj in &grid.detj.broadcast((4, y.ny(), y.nx())).unwrap()) {
*out = (-eflux - fflux)/detj
});
SAT_characteristics(k, y, grid, boundaries);
}
#[allow(non_snake_case)]
#[allow(unused)]
fn RHS_upwind<UO: UpwindOperator>(
k: &mut Field,
y: &Field,
grid: &Grid<UO>,
boundaries: &BoundaryTerms,
tmp: &mut (Field, Field, Field, Field),
) {
// fluxes(k, y, grid, tmp);
// dissipation(k, y, grid, tmp);
SAT_characteristics(k, y, grid, boundaries);
azip!((k in &mut k.0,
&detj in &grid.detj.broadcast((3, y.ny(), y.nx())).unwrap()) {
*k /= detj;
});
}
fn fluxes<SBP: SbpOperator>(k: [&mut Field; 2], y: &Field, grid: &Grid<SBP>) {
let j_dxi_dx = grid.detj_dxi_dx.view();
let j_dxi_dy = grid.detj_dxi_dy.view();
let j_deta_dx = grid.detj_deta_dx.view();
let j_deta_dy = grid.detj_deta_dy.view();
let rho = y.rho();
let rhou = y.rhou();
let rhov = y.rhov();
let e = y.e();
for j in 0..y.ny() {
for i in 0..y.nx() {
let rho = rho[(j, i)];
let rhou = rhou[(j, i)];
let rhov = rhov[(j, i)];
let e = e[(j, i)];
let p = pressure(GAMMA, rho, rhou, rhov, e);
let ef = [
rhou,
rhou * rhou / rho + p,
rhou * rhov / rho,
rhou * (e + p) / rho,
];
let ff = [
rhov,
rhou * rhov / rho,
rhov * rhov / rho + p,
rhov * (e + p) / rho,
];
for comp in 0..4 {
let eflux = j_dxi_dx[(j, i)] * ef[comp] + j_dxi_dy[(j, i)] * ff[comp];
let fflux = j_deta_dx[(j, i)] * ef[comp] + j_deta_dy[(j, i)] * ff[comp];
k[0][(comp, j, i)] = eflux;
k[1][(comp, j, i)] = fflux;
}
}
}
}
#[allow(unused)]
fn dissipation<UO: UpwindOperator>(
k: &mut Field,
y: &Field,
grid: &Grid<UO>,
tmp: &mut (Array2<f32>, Array2<f32>, Array2<f32>, Array2<f32>),
) {
todo!()
}
#[derive(Clone, Debug)]
pub enum Boundary {
This,
}
#[derive(Clone, Debug)]
pub struct BoundaryTerms {
pub north: Boundary,
pub south: Boundary,
pub east: Boundary,
pub west: Boundary,
}
#[allow(non_snake_case)]
/// Boundary conditions (SAT)
fn SAT_characteristics<SBP: SbpOperator>(
k: &mut Field,
y: &Field,
grid: &Grid<SBP>,
_boundaries: &BoundaryTerms,
) {
// North boundary
{
let hi = (k.ny() - 1) as f32 * SBP::h()[0];
let sign = -1.0;
let tau = 1.0;
let slice = s![y.nx() - 1, ..];
SAT_characteristic(
k.north_mut(),
y.north(),
y.south(), // Self South
hi,
sign,
tau,
grid.detj.slice(slice),
grid.detj_deta_dx.slice(slice),
grid.detj_deta_dy.slice(slice),
);
}
// South boundary
{
let hi = (k.ny() - 1) as f32 * SBP::h()[0];
let sign = 1.0;
let tau = -1.0;
let slice = s![0, ..];
SAT_characteristic(
k.south_mut(),
y.south(),
y.north(), // Self North
hi,
sign,
tau,
grid.detj.slice(slice),
grid.detj_deta_dx.slice(slice),
grid.detj_deta_dy.slice(slice),
);
}
// West Boundary
{
let hi = (k.nx() - 1) as f32 * SBP::h()[0];
let sign = 1.0;
let tau = -1.0;
let slice = s![.., 0];
println!("{:?}", slice);
SAT_characteristic(
k.west_mut(),
y.west(),
y.east(), // Self East
hi,
sign,
tau,
grid.detj.slice(slice),
grid.detj_dxi_dx.slice(slice),
grid.detj_dxi_dy.slice(slice),
);
}
// East Boundary
{
let hi = (k.nx() - 1) as f32 * SBP::h()[0];
let sign = -1.0;
let tau = 1.0;
let slice = s![.., y.nx() - 1];
SAT_characteristic(
k.east_mut(),
y.east(),
y.west(), // Self West
hi,
sign,
tau,
grid.detj.slice(slice),
grid.detj_dxi_dx.slice(slice),
grid.detj_dxi_dy.slice(slice),
);
}
}
#[allow(non_snake_case)]
/// Boundary conditions (SAT)
fn SAT_characteristic(
mut k: ArrayViewMut2<f32>,
y: ArrayView2<f32>,
z: ArrayView2<f32>, // Size 4 x n (all components in line)
hi: f32,
sign: f32,
tau: f32,
detj: ArrayView1<f32>,
detj_d_dx: ArrayView1<f32>,
detj_d_dy: ArrayView1<f32>,
) {
assert_eq!(detj.shape(), detj_d_dx.shape());
assert_eq!(detj.shape(), detj_d_dy.shape());
assert_eq!(y.shape(), z.shape());
assert_eq!(y.shape()[0], 4);
assert_eq!(y.shape()[1], detj.shape()[0]);
for i in 0..z.shape()[1] {
let rho = y[(0, i)];
let rhou = y[(1, i)];
let rhov = y[(2, i)];
let e = y[(3, i)];
let kx_ = detj_d_dx[i] / detj[i];
let ky_ = detj_d_dy[i] / detj[i];
let (kx, ky) = {
let r = f32::hypot(kx_, ky_);
(kx_ / r, ky_ / r)
};
let u = rhou / rho;
let v = rhov / rho;
let theta = kx * u + ky * v;
let p = pressure(GAMMA, rho, rhou, rhov, e);
let c = (GAMMA * p / rho).sqrt();
let phi2 = (GAMMA - 1.0) * (u * u + v * v) / 2.0;
let phi2_c2 = (phi2 + c * c) / (GAMMA - 1.0);
let T = [
[1.0, 0.0, 1.0, 1.0],
[u, ky, u + kx * c, u - kx * c],
[v, -kx, v + ky * c, v - ky * c],
[
phi2 / (GAMMA - 1.0),
ky * u - kx * v,
phi2_c2 + c * theta,
phi2_c2 - c * theta,
],
];
let U = kx_ * u + ky_ * v;
let L = [
U,
U,
U + c * f32::hypot(kx_, ky_),
U - c * f32::hypot(kx_, ky_),
];
let beta = 1.0 / (2.0 * c * c);
let TI = [
[
1.0 - phi2 / (c * c),
(GAMMA - 1.0) * u / (c * c),
(GAMMA - 1.0) * v / (c * c),
-(GAMMA - 1.0) / (c * c),
],
[-(ky * u - kx * v), ky, -kx, 0.0],
[
beta * (phi2 - c * theta),
beta * (kx * c - (GAMMA - 1.0) * u),
beta * (ky * c - (GAMMA - 1.0) * v),
beta * (GAMMA - 1.0),
],
[
beta * (phi2 + c * theta),
-beta * (kx * c + (GAMMA - 1.0) * u),
-beta * (ky * c + (GAMMA - 1.0) * v),
beta * (GAMMA - 1.0),
],
];
let res = [
rho - z[(0, i)],
rhou - z[(1, i)],
rhov - z[(2, i)],
e - z[(3, i)],
];
let mut TIres = [0.0; 4];
for row in 0..4 {
for col in 0..4 {
TIres[row] += TI[row][col] * res[col];
}
}
// L + sign(abs(L)) * TIres
let mut LTIres = [0.0; 4];
for row in 0..4 {
LTIres[row] = (L[row] + sign * L[row].abs()) * TIres[row];
}
// T*LTIres
let mut TLTIres = [0.0; 4];
for row in 0..4 {
for col in 0..4 {
TLTIres[row] += T[row][col] * LTIres[col];
}
}
for comp in 0..4 {
k[(comp, i)] += hi * tau * TLTIres[comp];
}
}
}
pub struct WorkBuffers {
y: Field,
buf: [Field; 4],
tmp: (Field, Field, Field, Field),
}
impl WorkBuffers {
pub fn new(nx: usize, ny: usize) -> Self {
let arr3 = Field::new(nx, ny);
Self {
y: arr3.clone(),
buf: [arr3.clone(), arr3.clone(), arr3.clone(), arr3.clone()],
tmp: (arr3.clone(), arr3.clone(), arr3.clone(), arr3),
}
}
}