1 files changed, 77 insertions, 0 deletions
diff --git a/Source/WarpXUtil.cpp b/Source/WarpXUtil.cpp
new file mode 100644
index 000000000..4edd41838
--- /dev/null
+++ b/Source/WarpXUtil.cpp
@@ -0,0 +1,77 @@
+#include <cmath>
+
+#include <WarpXUtil.H>
+#include <WarpXConst.H>
+#include <AMReX_ParmParse.H>
+
+using namespace amrex;
+
+void ReadBoostedFrameParameters(Real& gamma_boost, Real& beta_boost,
+                                Vector<int>& boost_direction)
+{
+    ParmParse pp("warpx");
+    pp.query("gamma_boost", gamma_boost);
+    beta_boost = std::sqrt(1.-1./pow(gamma_boost,2));
+    if( gamma_boost > 1. ) {
+        std::string s;
+        pp.get("boost_direction", s);
+        if (s == "x" || s == "X") {
+            boost_direction[0] = 1;
+        }
+#if (AMREX_SPACEDIM == 3)
+        else if (s == "y" || s == "Y") {
+            boost_direction[1] = 1;
+        }
+#endif
+        else if (s == "z" || s == "Z") {
+            boost_direction[2] = 1;
+        }
+        else {
+            const std::string msg = "Unknown boost_dir: "+s;
+            Abort(msg.c_str());
+        }
+        
+        AMREX_ALWAYS_ASSERT_WITH_MESSAGE( s == "z" || s == "Z" ,
+                                          "The boost must be in the z direction.");
+    }
+}
+
+void ConvertLabParamsToBoost()
+{
+
+    Real gamma_boost, beta_boost;
+    Vector<int> boost_direction {0,0,0};
+    
+    ReadBoostedFrameParameters(gamma_boost, beta_boost, boost_direction);
+        
+    if (gamma_boost <= 1.) return;
+    
+    Vector<Real> prob_lo(AMREX_SPACEDIM);
+    Vector<Real> prob_hi(AMREX_SPACEDIM);
+    
+    ParmParse pp("geometry");
+    pp.getarr("prob_lo",prob_lo,0,AMREX_SPACEDIM);
+    BL_ASSERT(prob_lo.size() == AMREX_SPACEDIM);
+    pp.getarr("prob_hi",prob_hi,0,AMREX_SPACEDIM);
+    BL_ASSERT(prob_hi.size() == AMREX_SPACEDIM);
+
+#if (AMREX_SPACEDIM == 3)
+    Vector<int> dim_map {0, 1, 2};
+#else
+    Vector<int> dim_map {0, 2};
+#endif
+
+    for (int idim = 0; idim < AMREX_SPACEDIM; ++idim)
+    {
+        if (boost_direction[dim_map[idim]]) {
+            amrex::Real convert_factor;
+            // Assume that the window travels with speed +c
+            convert_factor = 1./( gamma_boost * ( 1 - beta_boost ) );
+            prob_lo[idim] *= convert_factor;
+            prob_hi[idim] *= convert_factor;
+            break;
+        }
+    }    
+    pp.addarr("prob_lo", prob_lo);
+    pp.addarr("prob_hi", prob_hi);
+}