From f418ee4d2757364d2b666aad26bac94548f30f83 Mon Sep 17 00:00:00 2001
From: Remi Lehe <remi.lehe@normalesup.org>
Date: Mon, 27 Jan 2020 12:11:44 -0800
Subject: Implement cylindrical Yee algorithm

---
 .../CylindricalYeeAlgorithm.H                      | 96 +++++++++-------------
 1 file changed, 38 insertions(+), 58 deletions(-)

(limited to 'Source/FieldSolver/FiniteDifferenceSolver/FiniteDifferenceAlgorithms/CylindricalYeeAlgorithm.H')

diff --git a/Source/FieldSolver/FiniteDifferenceSolver/FiniteDifferenceAlgorithms/CylindricalYeeAlgorithm.H b/Source/FieldSolver/FiniteDifferenceSolver/FiniteDifferenceAlgorithms/CylindricalYeeAlgorithm.H
index 3f408479c..9258fdff4 100644
--- a/Source/FieldSolver/FiniteDifferenceSolver/FiniteDifferenceAlgorithms/CylindricalYeeAlgorithm.H
+++ b/Source/FieldSolver/FiniteDifferenceSolver/FiniteDifferenceAlgorithms/CylindricalYeeAlgorithm.H
@@ -5,97 +5,77 @@
 #include <AMReX_Array4.H>
 #include <AMReX_Gpu.H>
 
-struct YeeAlgorithm {
+struct CylindricalYeeAlgorithm {
 
     static void InitializeStencilCoefficients(
         std::array<amrex::Real,3>& cell_size,
-        amrex::Gpu::ManagedVector<amrex::Real>& stencil_coefs_x,
-        amrex::Gpu::ManagedVector<amrex::Real>& stencil_coefs_y,
+        amrex::Gpu::ManagedVector<amrex::Real>& stencil_coefs_r,
         amrex::Gpu::ManagedVector<amrex::Real>& stencil_coefs_z ) {
 
         // Store the inverse cell size along each direction in the coefficients
-        stencil_coefs_x.resize(1);
-        stencil_coefs_x[0] = 1./cell_size[0];
-        stencil_coefs_y.resize(1);
-        stencil_coefs_y[0] = 1./cell_size[1];
+        stencil_coefs_r.resize(1);
+        stencil_coefs_r[0] = 1./cell_size[0];  // 1./dr
         stencil_coefs_z.resize(1);
-        stencil_coefs_z[0] = 1./cell_size[2];
+        stencil_coefs_z[0] = 1./cell_size[2];  // 1./dz
     }
 
     AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
-    static amrex::Real UpwardDx(
+    static amrex::Real UpwardDr(
         amrex::Array4<amrex::Real> const& F,
-        amrex::Real const* coefs_x, int const n_coefs_x,
-        int const i, int const j, int const k ) {
+        amrex::Real const* coefs_r, int const n_coefs_r,
+        int const i, int const j, int const k, int const comp ) {
 
-        amrex::Real inv_dx = coefs_x[0];
-        return inv_dx*( F(i+1,j,k) - F(i,j,k) );
+        amrex::Real inv_dr = coefs_r[0];
+        return inv_dr*( F(i+1,j,k,comp) - F(i,j,k,comp) );
     };
 
     AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
-    static amrex::Real DownwardDx(
+    static amrex::Real DownwardDr(
         amrex::Array4<amrex::Real> const& F,
-        amrex::Real const* coefs_x, int const n_coefs_x,
-        int const i, int const j, int const k ) {
+        amrex::Real const* coefs_r, int const n_coefs_r,
+        int const i, int const j, int const k, int const comp ) {
 
-        amrex::Real inv_dx = coefs_x[0];
-        return inv_dx*( F(i,j,k) - F(i-1,j,k) );
-    };
-
-    AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
-    static amrex::Real UpwardDy(
-        amrex::Array4<amrex::Real> const& F,
-        amrex::Real const* coefs_y, int const n_coefs_y,
-        int const i, int const j, int const k ) {
-
-        #if defined WARPX_DIM_3D
-            amrex::Real inv_dy = coefs_y[0];
-            return inv_dy*( F(i,j+1,k) - F(i,j,k) );
-        #elif (defined WARPX_DIM_XZ)
-            return 0; // 2D Cartesian: derivative along y is 0
-        #endif
-    };
-
-    AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
-    static amrex::Real DownwardDy(
-        amrex::Array4<amrex::Real> const& F,
-        amrex::Real const* coefs_y, int const n_coefs_y,
-        int const i, int const j, int const k ) {
-
-        #if defined WARPX_DIM_3D
-            amrex::Real inv_dy = coefs_y[0];
-            return inv_dy*( F(i,j,k) - F(i,j-1,k) );
-        #elif (defined WARPX_DIM_XZ)
-            return 0; // 2D Cartesian: derivative along y is 0
-        #endif
+        amrex::Real inv_dr = coefs_r[0];
+        return inv_dr*( F(i,j,k,comp) - F(i-1,j,k,comp) );
     };
 
     AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
     static amrex::Real UpwardDz(
         amrex::Array4<amrex::Real> const& F,
         amrex::Real const* coefs_z, int const n_coefs_z,
-        int const i, int const j, int const k ) {
+        int const i, int const j, int const k, int const comp ) {
 
         amrex::Real inv_dz = coefs_z[0];
-        #if defined WARPX_DIM_3D
-            return inv_dz*( F(i,j,k+1) - F(i,j,k) );
-        #elif (defined WARPX_DIM_XZ)
-            return inv_dz*( F(i,j+1,k) - F(i,j,k) );
-        #endif
+        return inv_dz*( F(i,j+1,k,comp) - F(i,j,k,comp) );
     };
 
     AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
     static amrex::Real DownwardDz(
         amrex::Array4<amrex::Real> const& F,
         amrex::Real const* coefs_z, int const n_coefs_z,
-        int const i, int const j, int const k ) {
+        int const i, int const j, int const k, int const comp ) {
 
         amrex::Real inv_dz = coefs_z[0];
-        #if defined WARPX_DIM_3D
-            return inv_dz*( F(i,j,k) - F(i,j,k-1) );
-        #elif (defined WARPX_DIM_XZ)
-            return inv_dz*( F(i,j,k) - F(i,j-1,k) );
-        #endif
+        return inv_dz*( F(i,j,k,comp) - F(i,j-1,k,comp) );
+    };
+
+    AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
+    static amrex::Real DivideByR(
+        amrex::Array4<amrex::Real> const& F,
+        amrex::Real const r, int const dr, int const m,
+        int const i, int const j, int const k, int const comp) {
+
+        if (r != 0) {
+            return F(i,j,k,comp)/r;
+        } else { // r==0 ; singularity when dividing by r
+            if (m==1) {
+                // For m==1, F is linear in r, for small r
+                // Therefore, the formula below regularizes the singularity
+                return F(i+1,j,k,comp)/dr;
+            } else {
+                return 0;
+            }
+        }
     };
 
 };
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