Increase number of guard cells allocated with multi-J algorithm (#2377)

1 files changed, 19 insertions, 3 deletions

diff --git a/Source/Parallelization/GuardCellManager.cpp b/Source/Parallelization/GuardCellManager.cpp
index 6e3b46645..fcc3abcba 100644
--- a/Source/Parallelization/GuardCellManager.cpp
+++ b/Source/Parallelization/GuardCellManager.cpp
@@ -46,7 +46,9 @@ guardCellManager::Init (
     const amrex::Vector<amrex::Real> v_galilean,
     const amrex::Vector<amrex::Real> v_comoving,
     const bool safe_guard_cells,
-    const int do_electrostatic)
+    const int do_electrostatic,
+    const int do_multi_J,
+    const bool fft_do_time_averaging)
 {
     // When using subcycling, the particles on the fine level perform two pushes
     // before being redistributed ; therefore, we need one extra guard cell
@@ -122,8 +124,22 @@ guardCellManager::Init (
     {
         for (int i = 0; i < AMREX_SPACEDIM; i++)
         {
-            ng_alloc_Rho[i] += static_cast<int>(std::ceil(PhysConst::c * dt / dx[i]));
-            ng_alloc_J[i]   += static_cast<int>(std::ceil(PhysConst::c * dt / dx[i] * 0.5_rt));
+            amrex::Real dt_Rho = dt;
+            amrex::Real dt_J = 0.5_rt*dt;
+            if (do_multi_J) {
+                // With multi_J + time averaging, particles can move during 2*dt per PIC cycle.
+                if (fft_do_time_averaging){
+                    dt_Rho = 2._rt*dt;
+                    dt_J = 2._rt*dt;
+                }
+                // With multi_J but without time averaging, particles can move during dt per PIC
+                // cycle for the current deposition as well.
+                else {
+                    dt_J = dt;
+                }
+            }
+            ng_alloc_Rho[i] += static_cast<int>(std::ceil(PhysConst::c * dt_Rho / dx[i]));
+            ng_alloc_J[i]   += static_cast<int>(std::ceil(PhysConst::c * dt_J / dx[i]));
         }
     }