Filter Always ON by Default (#2031)

* Filter Always ON by Default

* Fix CI Tests

* Update Docs

* Fix CI Test dirichletbc

* Default WarpX::use_filter = 0 with RZ FDTD, Add Warnings

* Set WarpX::use_kspace_filter = true by Default, too

* RZ: Fix Bug with PSATD Binary and FDTD Runtime Solver

* Default use_kspace_filter = true, Fix Runtime Issue with Rho Functor

2 files changed, 32 insertions, 7 deletions

diff --git a/Source/Diagnostics/ComputeDiagFunctors/RhoFunctor.cpp b/Source/Diagnostics/ComputeDiagFunctors/RhoFunctor.cpp
index e8d7828cb..26d99f4a9 100644
--- a/Source/Diagnostics/ComputeDiagFunctors/RhoFunctor.cpp
+++ b/Source/Diagnostics/ComputeDiagFunctors/RhoFunctor.cpp
@@ -4,6 +4,7 @@
 #if (defined WARPX_DIM_RZ) && (defined WARPX_USE_PSATD)
     #include "FieldSolver/SpectralSolver/SpectralFieldData.H"
     #include "FieldSolver/SpectralSolver/SpectralSolverRZ.H"
+    #include "Utils/WarpXAlgorithmSelection.H"
 #endif
 #include "Particles/MultiParticleContainer.H"
 #include "Particles/WarpXParticleContainer.H"
@@ -54,11 +55,15 @@ RhoFunctor::operator() ( amrex::MultiFab& mf_dst, const int dcomp, const int /*i
 
 #if (defined WARPX_DIM_RZ) && (defined WARPX_USE_PSATD)
     using IdxAvg = SpectralFieldIndexTimeAveraging;
-    if (WarpX::use_kspace_filter) {
-        auto & solver = warpx.get_spectral_solver_fp(m_lev);
-        solver.ForwardTransform(m_lev, *rho, IdxAvg::rho_new);
-        solver.ApplyFilter(IdxAvg::rho_new);
-        solver.BackwardTransform(m_lev, *rho, IdxAvg::rho_new);
+    // Apply k-space filtering when using the PSATD solver
+    if (WarpX::maxwell_solver_id == MaxwellSolverAlgo::PSATD)
+    {
+        if (WarpX::use_kspace_filter) {
+            auto & solver = warpx.get_spectral_solver_fp(m_lev);
+            solver.ForwardTransform(m_lev, *rho, IdxAvg::rho_new);
+            solver.ApplyFilter(IdxAvg::rho_new);
+            solver.BackwardTransform(m_lev, *rho, IdxAvg::rho_new);
+        }
     }
 #endif
 
diff --git a/Source/WarpX.cpp b/Source/WarpX.cpp
index 927feb900..21cc5e4db 100644
--- a/Source/WarpX.cpp
+++ b/Source/WarpX.cpp
@@ -142,8 +142,8 @@ int WarpX::current_centering_noz = 2;
 bool WarpX::use_fdtd_nci_corr = false;
 bool WarpX::galerkin_interpolation = true;
 
-bool WarpX::use_filter        = false;
-bool WarpX::use_kspace_filter       = false;
+bool WarpX::use_filter = true;
+bool WarpX::use_kspace_filter       = true;
 bool WarpX::use_filter_compensation = false;
 
 bool WarpX::serialize_ics     = false;
@@ -556,6 +556,12 @@ WarpX::ReadParameters ()
         pp_warpx.query("n_buffer", n_buffer);
         pp_warpx.query("const_dt", const_dt);
 
+        // Filter currently not working with FDTD solver in RZ geometry: turn OFF by default
+        // (see https://github.com/ECP-WarpX/WarpX/issues/1943)
+#ifdef WARPX_DIM_RZ
+        if (WarpX::maxwell_solver_id != MaxwellSolverAlgo::PSATD) WarpX::use_filter = false;
+#endif
+
         // Read filter and fill IntVect filter_npass_each_dir with
         // proper size for AMREX_SPACEDIM
         pp_warpx.query("use_filter", use_filter);
@@ -568,12 +574,26 @@ WarpX::ReadParameters ()
         filter_npass_each_dir[2] = parse_filter_npass_each_dir[2];
 #endif
 
+        // TODO When k-space filtering will be implemented also for Cartesian geometries,
+        // this code block will have to be applied in all cases (remove #ifdef condition)
 #ifdef WARPX_DIM_RZ
         if (WarpX::maxwell_solver_id == MaxwellSolverAlgo::PSATD) {
             // With RZ spectral, only use k-space filtering
             use_kspace_filter = use_filter;
             use_filter = false;
         }
+        else // FDTD
+        {
+            // Filter currently not working with FDTD solver in RZ geometry
+            // (see https://github.com/ECP-WarpX/WarpX/issues/1943)
+            if (use_filter)
+            {
+                amrex::Print() << "\nWARNING:"
+                               << "\nFilter currently not working with FDTD solver in RZ geometry:"
+                               << "\nwe recommend setting warpx.use_filter = 0 in the input file.\n"
+                               << std::endl;
+            }
+        }
 #endif
 
         pp_warpx.query("num_mirrors", num_mirrors);