From 2dad6e2975931107be98205086eb11969e937ed1 Mon Sep 17 00:00:00 2001
From: WeiqunZhang <WeiqunZhang@lbl.gov>
Date: Thu, 30 Jul 2020 22:53:09 -0700
Subject: [PATCH] Average down faces (#1216)

New average_down_faces functions that take coarse Geometry and average down periodically.
---
 Src/Base/AMReX_MultiFabUtil.H   |  8 ++++++++
 Src/Base/AMReX_MultiFabUtil.cpp | 19 +++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/Src/Base/AMReX_MultiFabUtil.H b/Src/Base/AMReX_MultiFabUtil.H
index b84e81cc91d..0290fd2451a 100644
--- a/Src/Base/AMReX_MultiFabUtil.H
+++ b/Src/Base/AMReX_MultiFabUtil.H
@@ -71,6 +71,14 @@ namespace amrex
     void average_down_faces (const MultiFab& fine, MultiFab& crse,
                              const IntVect& ratio, int ngcrse=0);
 
+    //  This version takes periodicity into account.
+    void average_down_faces (const Array<const MultiFab*,AMREX_SPACEDIM>& fine,
+                             const Array<MultiFab*,AMREX_SPACEDIM>& crse,
+                             const IntVect& ratio, const Geometry& crse_geom);
+    //  This version takes periodicity into account.
+    void average_down_faces (const MultiFab& fine, MultiFab& crse,
+                             const IntVect& ratio, const Geometry& crse_geom);
+
     //! Average fine edge-based MultiFab onto crse edge-based MultiFab.
     void average_down_edges (const Vector<const MultiFab*>& fine,
                              const Vector<MultiFab*>& crse,
diff --git a/Src/Base/AMReX_MultiFabUtil.cpp b/Src/Base/AMReX_MultiFabUtil.cpp
index f558bf1a08e..d312cb676cf 100644
--- a/Src/Base/AMReX_MultiFabUtil.cpp
+++ b/Src/Base/AMReX_MultiFabUtil.cpp
@@ -501,6 +501,25 @@ namespace amrex
         }
     }
 
+    void average_down_faces (const Array<const MultiFab*,AMREX_SPACEDIM>& fine,
+                             const Array<MultiFab*,AMREX_SPACEDIM>& crse,
+                             const IntVect& ratio, const Geometry& crse_geom)
+    {
+        for (int idim = 0; idim < AMREX_SPACEDIM; ++idim)
+        {
+            average_down_faces(*fine[idim], *crse[idim], ratio, crse_geom);
+        }
+    }
+
+    void average_down_faces (const MultiFab& fine, MultiFab& crse,
+                             const IntVect& ratio, const Geometry& crse_geom)
+    {
+        MultiFab ctmp(amrex::coarsen(fine.boxArray(),ratio), fine.DistributionMap(),
+                      crse.nComp(), 0);
+        average_down_faces(fine, ctmp, ratio, 0);
+        crse.ParallelCopy(ctmp,0,0,crse.nComp(),0,0,crse_geom.periodicity());
+    }
+
     //! Average fine edge-based MultiFab onto crse edge-based MultiFab.
     //! This routine assumes that the crse BoxArray is a coarsened version of the fine BoxArray.
     void average_down_edges (const Vector<const MultiFab*>& fine, const Vector<MultiFab*>& crse,