1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
|
/* Copyright 2021
*
* This file is part of WarpX.
*
* License: BSD-3-Clause-LBNL
*/
#include "Utils/WarpXAlgorithmSelection.H"
#include "FiniteDifferenceSolver.H"
#include "Utils/WarpXConst.H"
#include <AMReX_Gpu.H>
using namespace amrex;
/**
* \brief Update the B field at the boundary, using the Silver-Mueller condition
*/
void FiniteDifferenceSolver::ApplySilverMuellerBoundary (
std::array< std::unique_ptr<amrex::MultiFab>, 3 >& Efield,
std::array< std::unique_ptr<amrex::MultiFab>, 3 >& Bfield,
amrex::Box domain_box,
amrex::Real const dt ) {
#ifdef WARPX_DIM_RZ
amrex::Abort("The Silver-Mueller boundary conditions cannot be used in RZ geometry.");
#else
// Ensure that we are using the Yee solver
if (m_fdtd_algo != MaxwellSolverAlgo::Yee) {
amrex::Abort("The Silver-Mueller boundary conditions can only be used with the Yee solver.");
}
// Ensure that we are using the cells the domain
domain_box.enclosedCells();
// Calculate relevant coefficients
amrex::Real const cdt_over_dx = PhysConst::c*dt*m_stencil_coefs_x[0];
amrex::Real const coef1_x = (1._rt - cdt_over_dx)/(1._rt + cdt_over_dx);
amrex::Real const coef2_x = 2._rt*cdt_over_dx/(1._rt + cdt_over_dx) / PhysConst::c;
#ifdef WARPX_DIM_3D
amrex::Real const cdt_over_dy = PhysConst::c*dt*m_stencil_coefs_y[0];
amrex::Real const coef1_y = (1._rt - cdt_over_dy)/(1._rt + cdt_over_dx);
amrex::Real const coef2_y = 2._rt*cdt_over_dy/(1._rt + cdt_over_dy) / PhysConst::c;
#endif
amrex::Real const cdt_over_dz = PhysConst::c*dt*m_stencil_coefs_z[0];
amrex::Real const coef1_z = (1._rt - cdt_over_dz)/(1._rt + cdt_over_dx);
amrex::Real const coef2_z = 2._rt*cdt_over_dz/(1._rt + cdt_over_dz) / PhysConst::c;
// Loop through the grids, and over the tiles within each grid
#ifdef AMREX_USE_OMP
#pragma omp parallel if (amrex::Gpu::notInLaunchRegion())
#endif
// tiling is usually set by TilingIfNotGPU()
// but here, we set it to false because of potential race condition,
// since we grow the tiles by one guard cell after creating them.
for ( MFIter mfi(*Efield[0], false); mfi.isValid(); ++mfi ) {
// Extract field data for this grid/tile
Array4<Real> const& Ex = Efield[0]->array(mfi);
Array4<Real> const& Ey = Efield[1]->array(mfi);
Array4<Real> const& Ez = Efield[2]->array(mfi);
Array4<Real> const& Bx = Bfield[0]->array(mfi);
Array4<Real> const& By = Bfield[1]->array(mfi);
Array4<Real> const& Bz = Bfield[2]->array(mfi);
// Extract the tileboxes for which to loop
Box tbx = mfi.tilebox(Bfield[0]->ixType().toIntVect());
Box tby = mfi.tilebox(Bfield[1]->ixType().toIntVect());
Box tbz = mfi.tilebox(Bfield[2]->ixType().toIntVect());
// We will modify the first (i.e. innermost) guard cell
// (if it is outside of the physical domain)
// Thus, the tileboxes here are grown by 1 guard cell
tbx.grow(1);
tby.grow(1);
tbz.grow(1);
// Loop over cells
amrex::ParallelFor(tbx, tby, tbz,
// Apply Boundary condition to Bx
[=] AMREX_GPU_DEVICE (int i, int j, int k){
#ifdef WARPX_DIM_3D
// At the +y boundary (innermost guard cell)
if ( j==domain_box.bigEnd(1)+1 )
Bx(i,j,k) = coef1_y * Bx(i,j,k) + coef2_y * Ez(i,j,k);
// At the -y boundary (innermost guard cell)
if ( j==domain_box.smallEnd(1)-1 )
Bx(i,j,k) = coef1_y * Bx(i,j,k) - coef2_y * Ez(i,j+1,k);
// At the +z boundary (innermost guard cell)
if ( k==domain_box.bigEnd(2)+1 )
Bx(i,j,k) = coef1_z * Bx(i,j,k) - coef2_z * Ey(i,j,k);
// At the -z boundary (innermost guard cell)
if ( k==domain_box.smallEnd(2)-1 )
Bx(i,j,k) = coef1_z * Bx(i,j,k) + coef2_z * Ey(i,j,k+1);
#elif WARPX_DIM_XZ
// At the +z boundary (innermost guard cell)
if ( j==domain_box.bigEnd(1)+1 )
Bx(i,j,k) = coef1_z * Bx(i,j,k) - coef2_z * Ey(i,j,k);
// At the -z boundary (innermost guard cell)
if ( j==domain_box.smallEnd(1)-1 )
Bx(i,j,k) = coef1_z * Bx(i,j,k) + coef2_z * Ey(i,j+1,k);
#endif
},
// Apply Boundary condition to By
[=] AMREX_GPU_DEVICE (int i, int j, int k){
// At the +x boundary (innermost guard cell)
if ( i==domain_box.bigEnd(0)+1 )
By(i,j,k) = coef1_x * By(i,j,k) - coef2_x * Ez(i,j,k);
// At the -x boundary (innermost guard cell)
if ( i==domain_box.smallEnd(0)-1 )
By(i,j,k) = coef1_x * By(i,j,k) + coef2_x * Ez(i+1,j,k);
#ifdef WARPX_DIM_3D
// At the +z boundary (innermost guard cell)
if ( k==domain_box.bigEnd(2)+1 )
By(i,j,k) = coef1_z * By(i,j,k) + coef2_z * Ex(i,j,k);
// At the -z boundary (innermost guard cell)
if ( k==domain_box.smallEnd(2)-1 )
By(i,j,k) = coef1_z * By(i,j,k) - coef2_z * Ex(i,j,k+1);
#elif WARPX_DIM_XZ
// At the +z boundary (innermost guard cell)
if ( j==domain_box.bigEnd(1)+1 )
By(i,j,k) = coef1_z * By(i,j,k) + coef2_z * Ex(i,j,k);
// At the -z boundary (innermost guard cell)
if ( j==domain_box.smallEnd(1)-1 )
By(i,j,k) = coef1_z * By(i,j,k) - coef2_z * Ex(i,j+1,k);
#endif
},
// Apply Boundary condition to Bz
[=] AMREX_GPU_DEVICE (int i, int j, int k){
// At the +x boundary (innermost guard cell)
if ( i==domain_box.bigEnd(0)+1 )
Bz(i,j,k) = coef1_x * Bz(i,j,k) + coef2_x * Ey(i,j,k);
// At the -x boundary (innermost guard cell)
if ( i==domain_box.smallEnd(0)-1 )
Bz(i,j,k) = coef1_x * Bz(i,j,k) - coef2_x * Ey(i+1,j,k);
#ifdef WARPX_DIM_3D
// At the +y boundary (innermost guard cell)
if ( j==domain_box.bigEnd(1)+1 )
Bz(i,j,k) = coef1_y * Bz(i,j,k) - coef2_y * Ex(i,j,k);
// At the -y boundary (innermost guard cell)
if ( j==domain_box.smallEnd(1)-1 )
Bz(i,j,k) = coef1_y * Bz(i,j,k) + coef2_y * Ex(i,j+1,k);
#endif
}
);
}
#endif // WARPX_DIM_RZ
}
|
