Make the maxiumum dt change between time steps a runtime variable. (#100

)

src/incflo.H

@@ -342,6 +342,7 @@ private:
     amrex::Real m_cfl = amrex::Real(0.5);
     amrex::Real m_fixed_dt = amrex::Real(-1.);
     amrex::Real m_init_shrink = amrex::Real(0.1);
+    amrex::Real m_dt_change_max = amrex::Real(1.1);
 
     // Initial projection / iterations
     bool m_do_initial_proj    = true;

src/incflo_compute_dt.cpp

@@ -231,7 +231,7 @@ void incflo::ComputeDt (int initialization, bool explicit_diffusion)
 
     // Don't let the timestep grow by more than 10% per step
     // unless the previous time step was unduly shrunk to match m_plot_per_exact
-    Real allowed_change_factor = Real(1.1);
+    Real allowed_change_factor = m_dt_change_max;
     if( (m_dt > Real(0.0)) && !(m_plot_per_exact > 0 && m_last_plt == m_nstep && m_nstep > 0) )
     {
         dt_new = amrex::min(dt_new, allowed_change_factor * m_prev_dt);

src/setup/init.cpp

@@ -48,6 +48,12 @@ void incflo::ReadParameters ()
             amrex::Abort("We require m_init_shrink <= 1.0");
         }
 
+        // This limits dt growth per time step
+        pp.query("dt_change_max", m_dt_change_max);
+        if ( m_dt_change_max < 1.0 || m_dt_change_max > 1.1 ) {
+            amrex::Abort("We require 1. < dt_change_max <= 1.1");
+        }
+
         // Physics
         pp.queryarr("delp", m_delp, 0, AMREX_SPACEDIM);
         pp.queryarr("gravity", m_gravity, 0, AMREX_SPACEDIM);