colin/fdtd-coremem
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Add this new UpdateMethod enum and PmlState to allow for future pml implementation

Browse Source 
I don't like the mutability peculiarities around it, but it should do
the job for now.
This commit is contained in:
Colin
2021-05-29 14:00:06 -07:00
parent cb0c899194
commit edf93d0a24
2 changed files with 116 additions and 55 deletions
Download Patch File Download Diff File Expand all files Collapse all files

38
src/mat.rs
View File

@@ -1,6 +1,7 @@
use crate::{CellState, consts};
use crate::flt::{Flt, Real};
use crate::geom::{Line2d, Vec2, Vec3, Polygon2d};
use crate::sim::{UpdateMethod, UpdateMethodMut};
use lazy_static::lazy_static;
use log::{debug, trace};
@@ -10,10 +11,9 @@ use std::cmp::Ordering;
#[enum_dispatch]
pub trait Material {
/// Return \sigma, the electrical conductivity.
/// For a vacuum, this is zero. For a perfect conductor, \inf.
fn conductivity(&self) -> Vec3 {
Default::default()
fn update_method_mut<'a>(&'a mut self) -> UpdateMethodMut<'a> {
// by default, behave as a vacuum
UpdateMethodMut::Maxwell { conductivity: Vec3::zero() }
}
/// Return the magnetization.
fn m(&self) -> Vec3 {
@@ -27,12 +27,27 @@ pub trait Material {
}
pub trait MaterialExt {
fn update_method<'a>(&'a self) -> UpdateMethod<'a>;
fn conductivity(&self) -> Vec3;
fn is_vacuum(&self) -> bool;
}
impl<M: Material> MaterialExt for M {
fn update_method<'a>(&'a self) -> UpdateMethod<'a> {
match unsafe { &mut *(self as *const M as *mut M) }.update_method_mut() {
UpdateMethodMut::Maxwell { conductivity } => UpdateMethod::Maxwell { conductivity},
UpdateMethodMut::Pml { pml, pseudo_conductivity } =>
UpdateMethod::Pml { pml, pseudo_conductivity },
}
}
fn conductivity(&self) -> Vec3 {
match self.update_method() {
UpdateMethod::Maxwell { conductivity } => conductivity,
UpdateMethod::Pml { pseudo_conductivity, .. } => pseudo_conductivity,
}
}
fn is_vacuum(&self) -> bool {
self.conductivity() == Default::default()
self.conductivity() == Vec3::zero()
}
}
@@ -54,8 +69,8 @@ impl Static {
}
impl Material for Static {
fn conductivity(&self) -> Vec3 {
self.conductivity
fn update_method_mut<'a>(&'a mut self) -> UpdateMethodMut<'a> {
UpdateMethodMut::Maxwell { conductivity: self.conductivity }
}
fn m(&self) -> Vec3 {
self.m
@@ -89,8 +104,8 @@ impl Conductor {
}
impl Material for Conductor {
fn conductivity(&self) -> Vec3 {
self.conductivity
fn update_method_mut<'a>(&'a mut self) -> UpdateMethodMut<'a> {
UpdateMethodMut::Maxwell { conductivity: self.conductivity }
}
}
@@ -102,9 +117,10 @@ pub trait PiecewiseLinearFerromagnet {
}
impl<T: PiecewiseLinearFerromagnet> Material for T {
fn conductivity(&self) -> Vec3 {
fn update_method_mut<'a>(&'a mut self) -> UpdateMethodMut<'a> {
let c = T::conductivity();
Vec3::new(c, c, c)
let conductivity = Vec3::new(c, c, c);
UpdateMethodMut::Maxwell { conductivity }
}
fn m(&self) -> Vec3 {
self.m()

133
src/sim.rs
View File

@@ -1,6 +1,6 @@
use crate::{flt::{Flt, Real}, consts};
use crate::geom::{Coord, Cube, Index, InvertedRegion, Meters, Region, Vec3, Vec3u};
use crate::mat::{self, GenericMaterial, Material};
use crate::mat::{self, GenericMaterial, Material, MaterialExt as _};
use crate::stim::AbstractStimulus;
use dyn_clone::{self, DynClone};
use log::trace;
@@ -13,6 +13,43 @@ use std::iter::Sum;
pub type StaticSim = SimState<mat::Static>;
#[derive(Default, Copy, Clone, PartialEq)]
pub struct PmlState {
/// Auxiliary field used when stepping E
aux_e: Vec3,
/// Auxiliary field used when stepping B
aux_b: Vec3,
}
impl PmlState {
pub fn new() -> Self {
Self::default()
}
}
/// Used to instruct the Sim how to advance the state at a given location.
///
/// `UpdateMethod::Maxwell` means to apply Maxwell's equations as usual, with
/// the provided parameters.
///
/// `UpdateMethod::Pml` means to apply a modified formulation of Maxwell's equations
/// which are reflectionless for normally incident waves. This allows the material to behave
/// as a "Perfectly Matched Layer" (PML), dissipating energy AS IF it was a conductor
/// with the provided `pseudo_conductivity`.
#[derive(PartialEq)]
pub enum UpdateMethodMut<'a> {
/// `conductivity` is traditionally represented by $\sigma$
Maxwell { conductivity: Vec3 },
Pml { pml: &'a mut PmlState, pseudo_conductivity: Vec3 },
}
#[derive(PartialEq)]
pub enum UpdateMethod<'a> {
/// `conductivity` is traditionally represented by $\sigma$
Maxwell { conductivity: Vec3 },
Pml { pml: &'a PmlState, pseudo_conductivity: Vec3 },
}
pub trait GenericSim: Send + Sync + DynClone {
fn sample(&self, pos: Meters) -> Cell<mat::Static>;
fn impulse_e_meters(&mut self, pos: Meters, amount: Vec3);
@@ -580,6 +617,7 @@ impl<M: Material> Cell<M> {
}
pub fn current_density(&self) -> Vec3 {
// TODO: does this make sense for Pml?
let conductivity = self.mat.conductivity();
self.e().elem_mul(conductivity)
}
@@ -664,7 +702,6 @@ impl<M: Material> Cell<M> {
let twice_delta_t = TWO() * delta_t;
let half_delta_t = HALF() * delta_t;
let h_prev = self.h();
let b_prev = self.b();
let (delta_ey_x, delta_ez_x) = match (neighbors.right, neighbors.left) {
@@ -691,28 +728,33 @@ impl<M: Material> Cell<M> {
// \nabla x E
let nabla_e = Vec3::from((delta_ez_y - delta_ey_z, delta_ex_z - delta_ez_x, delta_ey_x - delta_ex_y));
// From: $\nabla x E = -dB/dt$
let db_dt = solve_step_diff_eq(
nabla_e,
-Vec3::unit(), // dB/dt coeff
Vec3::zero(), // B coeff
Vec3::zero(), // \int B coeff
Vec3::zero(), // \int \int B coeff
delta_t,
b_prev,
Vec3::zero(), // b_int_prev,
Vec3::zero(), // b_int_int_prev
);
match self.mat.update_method() {
UpdateMethod::Maxwell { .. } => {
// From: $\nabla x E = -dB/dt$
let db_dt = solve_step_diff_eq(
nabla_e,
-Vec3::unit(), // dB/dt coeff
Vec3::zero(), // B coeff
Vec3::zero(), // \int B coeff
Vec3::zero(), // \int \int B coeff
delta_t,
b_prev,
Vec3::zero(), // b_int_prev,
Vec3::zero(), // b_int_int_prev
);
// Maxwell's equation gave us delta_b. Material parameters let us turn that into h.
let delta_b = db_dt * twice_delta_t;
let h = self.mat.step_h(&self.state, delta_b);
Cell {
state: CellState {
h: h.into(),
..self.state
},
mat: self.mat,
// Maxwell's equation gave us delta_b. Material parameters let us turn that into h.
let delta_b = db_dt * twice_delta_t;
let h = self.mat.step_h(&self.state, delta_b);
Cell {
state: CellState {
h: h.into(),
..self.state
},
mat: self.mat,
}
}
UpdateMethod::Pml { .. } => unimplemented!(),
}
}
@@ -751,9 +793,6 @@ impl<M: Material> Cell<M> {
use consts::real::{EPS0, HALF, THIRD, TWO, ZERO};
let twice_delta_t = TWO() * delta_t;
let sigma = self.mat.conductivity();
let e_prev = self.e();
let (delta_hy_x, delta_hz_x) = match (neighbors.left, neighbors.right) {
@@ -780,26 +819,32 @@ impl<M: Material> Cell<M> {
// \nabla x H
let nabla_h = Vec3::from((delta_hz_y - delta_hy_z, delta_hx_z - delta_hz_x, delta_hy_x - delta_hx_y));
match self.mat.update_method() {
UpdateMethod::Maxwell { conductivity } => {
let sigma = conductivity;
// From: $\nabla x H = \epsilon_0 dE/dt + \sigma E$
let de_dt = solve_step_diff_eq(
nabla_h,
Vec3::unit()*EPS0(), // dE/dt coeff
sigma, // E coeff
Vec3::zero(), // \int E coeff
Vec3::zero(), // \int \int E coeff
delta_t,
e_prev,
Vec3::zero(), // e_int_prev
Vec3::zero(), // e_int_int_prev
);
// From: $\nabla x H = \epsilon_0 dE/dt + \sigma E$
let de_dt = solve_step_diff_eq(
nabla_h,
Vec3::unit()*EPS0(), // dE/dt coeff
sigma, // E coeff
Vec3::zero(), // \int E coeff
Vec3::zero(), // \int \int E coeff
delta_t,
e_prev,
Vec3::zero(), // e_int_prev
Vec3::zero(), // e_int_int_prev
);
Cell {
state: CellState {
e: e_prev + de_dt*twice_delta_t,
..self.state
},
mat: self.mat,
Cell {
state: CellState {
e: e_prev + de_dt*twice_delta_t,
..self.state
},
mat: self.mat,
}
}
UpdateMethod::Pml { .. } => unimplemented!(),
}
}
}