WarpX class: make do_divb_cleaning_external a private member variable (#5598)

This PR changes `do_divb_cleaning_external` from a static WarpX class
variable to a private member variable (renamed
`m_do_divb_cleaning_external`).
This is a small step towards reducing the use of static variables in the
WarpX class.

Author: lucafedeli88

Source/Initialization/WarpXInitData.cpp

@@ -590,7 +590,7 @@ WarpX::InitData ()
     WriteUsedInputsFile();
 
     // Run div cleaner here on loaded external fields
-    if (WarpX::do_divb_cleaning_external) {
+    if (m_do_divb_cleaning_external) {
         WarpX::ProjectionCleanDivB();
     }
 

Source/WarpX.H

@@ -290,10 +290,6 @@ public:
     //! Solve additional Maxwell equation for G in order to control errors in magnetic Gauss' law
     static bool do_divb_cleaning;
 
-    //! Solve Poisson equation when loading an external magnetic field to clean divergence
-    //! This is useful to remove errors that could lead to non-zero B field divergence
-    static bool do_divb_cleaning_external;
-
     //! Order of the particle shape factors (splines) along x
     static int nox;
     //! Order of the particle shape factors (splines) along y
@@ -1582,6 +1578,10 @@ private:
     int noy_fft = 16;
     int noz_fft = 16;
 
+    //! Solve Poisson equation when loading an external magnetic field to clean divergence
+    //! This is useful to remove errors that could lead to non-zero B field divergence
+    bool m_do_divb_cleaning_external = false;
+
     //! Domain decomposition on Level 0
     amrex::IntVect numprocs{0};
 

Source/WarpX.cpp

@@ -118,7 +118,6 @@ int WarpX::max_particle_its_in_implicit_scheme = 21;
 ParticleReal WarpX::particle_tol_in_implicit_scheme = 1.e-10;
 bool WarpX::do_dive_cleaning = false;
 bool WarpX::do_divb_cleaning = false;
-bool WarpX::do_divb_cleaning_external = false;
 bool WarpX::do_single_precision_comms = false;
 
 bool WarpX::do_shared_mem_charge_deposition = false;
@@ -1064,9 +1063,9 @@ WarpX::ReadParameters ()
                 || WarpX::electrostatic_solver_id == ElectrostaticSolverAlgo::LabFrameElectroMagnetostatic)
                 && WarpX::poisson_solver_id == PoissonSolverAlgo::Multigrid)))
         {
-            do_divb_cleaning_external = true;
+            m_do_divb_cleaning_external = true;
         }
-        pp_warpx.query("do_divb_cleaning_external", do_divb_cleaning_external);
+        pp_warpx.query("do_divb_cleaning_external", m_do_divb_cleaning_external);
 
         // If true, the current is deposited on a nodal grid and centered onto
         // a staggered grid. Setting warpx.do_current_centering=1 makes sense