merged with upstream dev

1 files changed, 225 insertions, 0 deletions

diff --git a/Source/FieldSolver/SpectralSolver/SpectralAlgorithms/PsatdAlgorithm.cpp b/Source/FieldSolver/SpectralSolver/SpectralAlgorithms/PsatdAlgorithm.cpp
new file mode 100644
index 000000000..8dd2a830f
--- /dev/null
+++ b/Source/FieldSolver/SpectralSolver/SpectralAlgorithms/PsatdAlgorithm.cpp
@@ -0,0 +1,225 @@
+#include <PsatdAlgorithm.H>
+#include <WarpXConst.H>
+#include <cmath>
+
+using namespace amrex;
+
+/* \brief Initialize coefficients for the update equation */
+PsatdAlgorithm::PsatdAlgorithm(const SpectralKSpace& spectral_kspace,
+                         const DistributionMapping& dm,
+                         const int norder_x, const int norder_y,
+                         const int norder_z, const bool nodal, const Real dt)
+     // Initialize members of base class
+     : SpectralBaseAlgorithm( spectral_kspace, dm,
+                              norder_x, norder_y, norder_z, nodal )
+{
+    const BoxArray& ba = spectral_kspace.spectralspace_ba;
+
+    // Allocate the arrays of coefficients
+    C_coef = SpectralCoefficients(ba, dm, 1, 0);
+    S_ck_coef = SpectralCoefficients(ba, dm, 1, 0);
+    X1_coef = SpectralCoefficients(ba, dm, 1, 0);
+    X2_coef = SpectralCoefficients(ba, dm, 1, 0);
+    X3_coef = SpectralCoefficients(ba, dm, 1, 0);
+
+    InitializeCoefficience(spectral_kspace, dm, dt);
+//    // Fill them with the right values:
+//    // Loop over boxes and allocate the corresponding coefficients
+//    // for each box owned by the local MPI proc
+//    for (MFIter mfi(ba, dm); mfi.isValid(); ++mfi){
+//
+//        //const Box& bx = ba[mfi];
+//        const Box bx = ba[mfi];
+//
+//        // Extract pointers for the k vectors
+//        const Real* modified_kx = modified_kx_vec[mfi].dataPtr();
+//#if (AMREX_SPACEDIM==3)
+//        const Real* modified_ky = modified_ky_vec[mfi].dataPtr();
+//#endif
+//        const Real* modified_kz = modified_kz_vec[mfi].dataPtr();
+//        // Extract arrays for the coefficients
+//        Array4<Real> C = C_coef[mfi].array();
+//        Array4<Real> S_ck = S_ck_coef[mfi].array();
+//        Array4<Real> X1 = X1_coef[mfi].array();
+//        Array4<Real> X2 = X2_coef[mfi].array();
+//        Array4<Real> X3 = X3_coef[mfi].array();
+//
+//        // Loop over indices within one box
+//        ParallelFor(bx,
+//        [=] AMREX_GPU_DEVICE(int i, int j, int k) noexcept
+//        {
+//            // Calculate norm of vector
+//            const Real k_norm = std::sqrt(
+//                std::pow(modified_kx[i], 2) +
+//#if (AMREX_SPACEDIM==3)
+//                std::pow(modified_ky[j], 2) +
+//                std::pow(modified_kz[k], 2));
+//#else
+//                std::pow(modified_kz[j], 2));
+//#endif
+//
+//            // Calculate coefficients
+//            constexpr Real c = PhysConst::c;
+//            constexpr Real ep0 = PhysConst::ep0;
+//            if (k_norm != 0){
+//                C(i,j,k) = std::cos(c*k_norm*dt);
+//                S_ck(i,j,k) = std::sin(c*k_norm*dt)/(c*k_norm);
+//                X1(i,j,k) = (1. - C(i,j,k))/(ep0 * c*c * k_norm*k_norm);
+//                X2(i,j,k) = (1. - S_ck(i,j,k)/dt)/(ep0 * k_norm*k_norm);
+//                X3(i,j,k) = (C(i,j,k) - S_ck(i,j,k)/dt)/(ep0 * k_norm*k_norm);
+//            } else { // Handle k_norm = 0, by using the analytical limit
+//                C(i,j,k) = 1.;
+//                S_ck(i,j,k) = dt;
+//                X1(i,j,k) = 0.5 * dt*dt / ep0;
+//                X2(i,j,k) = c*c * dt*dt / (6.*ep0);
+//                X3(i,j,k) = - c*c * dt*dt / (3.*ep0);
+//            }
+//        });
+//    }
+};
+
+/* Advance the E and B field in spectral space (stored in `f`)
+ * over one time step */
+void
+PsatdAlgorithm::pushSpectralFields(SpectralFieldData& f) const{
+
+    // Loop over boxes
+    for (MFIter mfi(f.fields); mfi.isValid(); ++mfi){
+
+        const Box& bx = f.fields[mfi].box();
+
+        // Extract arrays for the fields to be updated
+        Array4<Complex> fields = f.fields[mfi].array();
+        // Extract arrays for the coefficients
+        Array4<const Real> C_arr = C_coef[mfi].array();
+        Array4<const Real> S_ck_arr = S_ck_coef[mfi].array();
+        Array4<const Real> X1_arr = X1_coef[mfi].array();
+        Array4<const Real> X2_arr = X2_coef[mfi].array();
+        Array4<const Real> X3_arr = X3_coef[mfi].array();
+        // Extract pointers for the k vectors
+        const Real* modified_kx_arr = modified_kx_vec[mfi].dataPtr();
+#if (AMREX_SPACEDIM==3)
+        const Real* modified_ky_arr = modified_ky_vec[mfi].dataPtr();
+#endif
+        const Real* modified_kz_arr = modified_kz_vec[mfi].dataPtr();
+
+        // Loop over indices within one box
+        ParallelFor(bx,
+        [=] AMREX_GPU_DEVICE(int i, int j, int k) noexcept
+        {
+            // Record old values of the fields to be updated
+            using Idx = SpectralFieldIndex;
+            const Complex Ex_old = fields(i,j,k,Idx::Ex);
+            const Complex Ey_old = fields(i,j,k,Idx::Ey);
+            const Complex Ez_old = fields(i,j,k,Idx::Ez);
+            const Complex Bx_old = fields(i,j,k,Idx::Bx);
+            const Complex By_old = fields(i,j,k,Idx::By);
+            const Complex Bz_old = fields(i,j,k,Idx::Bz);
+            // Shortcut for the values of J and rho
+            const Complex Jx = fields(i,j,k,Idx::Jx);
+            const Complex Jy = fields(i,j,k,Idx::Jy);
+            const Complex Jz = fields(i,j,k,Idx::Jz);
+            const Complex rho_old = fields(i,j,k,Idx::rho_old);
+            const Complex rho_new = fields(i,j,k,Idx::rho_new);
+            // k vector values, and coefficients
+            const Real kx = modified_kx_arr[i];
+#if (AMREX_SPACEDIM==3)
+            const Real ky = modified_ky_arr[j];
+            const Real kz = modified_kz_arr[k];
+#else
+            constexpr Real ky = 0;
+            const Real kz = modified_kz_arr[j];
+#endif
+            constexpr Real c2 = PhysConst::c*PhysConst::c;
+            constexpr Real inv_ep0 = 1./PhysConst::ep0;
+            const Complex I = Complex{0,1};
+            const Real C = C_arr(i,j,k);
+            const Real S_ck = S_ck_arr(i,j,k);
+            const Real X1 = X1_arr(i,j,k);
+            const Real X2 = X2_arr(i,j,k);
+            const Real X3 = X3_arr(i,j,k);
+
+            // Update E (see WarpX online documentation: theory section)
+            fields(i,j,k,Idx::Ex) = C*Ex_old
+                        + S_ck*(c2*I*(ky*Bz_old - kz*By_old) - inv_ep0*Jx)
+                        - I*(X2*rho_new - X3*rho_old)*kx;
+            fields(i,j,k,Idx::Ey) = C*Ey_old
+                        + S_ck*(c2*I*(kz*Bx_old - kx*Bz_old) - inv_ep0*Jy)
+                        - I*(X2*rho_new - X3*rho_old)*ky;
+            fields(i,j,k,Idx::Ez) = C*Ez_old
+                        + S_ck*(c2*I*(kx*By_old - ky*Bx_old) - inv_ep0*Jz)
+                        - I*(X2*rho_new - X3*rho_old)*kz;
+            // Update B (see WarpX online documentation: theory section)
+            fields(i,j,k,Idx::Bx) = C*Bx_old
+                        - S_ck*I*(ky*Ez_old - kz*Ey_old)
+                        +   X1*I*(ky*Jz     - kz*Jy);
+            fields(i,j,k,Idx::By) = C*By_old
+                        - S_ck*I*(kz*Ex_old - kx*Ez_old)
+                        +   X1*I*(kz*Jx     - kx*Jz);
+            fields(i,j,k,Idx::Bz) = C*Bz_old
+                        - S_ck*I*(kx*Ey_old - ky*Ex_old)
+                        +   X1*I*(kx*Jy     - ky*Jx);
+        });
+    }
+};
+
+void PsatdAlgorithm::InitializeCoefficience(const SpectralKSpace& spectral_kspace,
+                                    const amrex::DistributionMapping& dm,
+                                    const amrex::Real dt)
+{
+    const BoxArray& ba = spectral_kspace.spectralspace_ba;
+    // Fill them with the right values:
+    // Loop over boxes and allocate the corresponding coefficients
+    // for each box owned by the local MPI proc
+    for (MFIter mfi(ba, dm); mfi.isValid(); ++mfi){
+
+        //const Box& bx = ba[mfi];
+        const Box bx = ba[mfi];
+
+        // Extract pointers for the k vectors
+        const Real* modified_kx = modified_kx_vec[mfi].dataPtr();
+#if (AMREX_SPACEDIM==3)
+        const Real* modified_ky = modified_ky_vec[mfi].dataPtr();
+#endif
+        const Real* modified_kz = modified_kz_vec[mfi].dataPtr();
+        // Extract arrays for the coefficients
+        Array4<Real> C = C_coef[mfi].array();
+        Array4<Real> S_ck = S_ck_coef[mfi].array();
+        Array4<Real> X1 = X1_coef[mfi].array();
+        Array4<Real> X2 = X2_coef[mfi].array();
+        Array4<Real> X3 = X3_coef[mfi].array();
+
+        // Loop over indices within one box
+        ParallelFor(bx,
+        [=] AMREX_GPU_DEVICE(int i, int j, int k) noexcept
+        {
+            // Calculate norm of vector
+            const Real k_norm = std::sqrt(
+                std::pow(modified_kx[i], 2) +
+#if (AMREX_SPACEDIM==3)
+                std::pow(modified_ky[j], 2) +
+                std::pow(modified_kz[k], 2));
+#else
+                std::pow(modified_kz[j], 2));
+#endif
+
+
+            // Calculate coefficients
+            constexpr Real c = PhysConst::c;
+            constexpr Real ep0 = PhysConst::ep0;
+            if (k_norm != 0){
+                C(i,j,k) = std::cos(c*k_norm*dt);
+                S_ck(i,j,k) = std::sin(c*k_norm*dt)/(c*k_norm);
+                X1(i,j,k) = (1. - C(i,j,k))/(ep0 * c*c * k_norm*k_norm);
+                X2(i,j,k) = (1. - S_ck(i,j,k)/dt)/(ep0 * k_norm*k_norm);
+                X3(i,j,k) = (C(i,j,k) - S_ck(i,j,k)/dt)/(ep0 * k_norm*k_norm);
+            } else { // Handle k_norm = 0, by using the analytical limit
+                C(i,j,k) = 1.;
+                S_ck(i,j,k) = dt;
+                X1(i,j,k) = 0.5 * dt*dt / ep0;
+                X2(i,j,k) = c*c * dt*dt / (6.*ep0);
+                X3(i,j,k) = - c*c * dt*dt / (3.*ep0);
+            }
+        });
+     }
+}