# HG changeset patch
# User calpe  <miguel.calpe.linares@gmail.com>
# Date 1537268577 -7200
#      Tue Sep 18 13:02:57 2018 +0200
# Node ID 670c4abb49dcf2e34c2a961b71f2ea7c92419892
# Parent  3194c26bc6baaf2fbaf02ac6d134c8bde14c1b56
Add parameter cfl_coef_group.

diff --git a/fluidsim/solvers/ns2d/strat/time_stepping.py b/fluidsim/solvers/ns2d/strat/time_stepping.py
--- a/fluidsim/solvers/ns2d/strat/time_stepping.py
+++ b/fluidsim/solvers/ns2d/strat/time_stepping.py
@@ -25,6 +25,13 @@
 
     """
 
+    @classmethod
+    def _complete_params_with_default(cls, params):
+        super(TimeSteppingPseudoSpectralStrat, cls)._complete_params_with_default(params)
+
+        # Add parameter coefficient CFL GROUP VELOCITY
+        params.time_stepping._set_attrib("cfl_coef_group", None)
+
     def _init_compute_time_step(self):
         """
         Initialization compute time step solver ns2d.strat.
@@ -33,7 +40,12 @@
 
         # Coefficients dt
         self.coef_deltat_dispersion_relation = 1.0
-        self.coef_group = 1.0
+
+        if self.params.time_stepping.cfl_coef_group:
+            self.coef_group = self.params.time_stepping.cfl_coef_group
+        else:
+            self.coef_group = 1.0
+
         self.coef_phase = 1.0
 
         has_vars = self.sim.state.has_vars
@@ -141,14 +153,23 @@
         else:
             deltat_CFL = self.deltat_max
 
+        # maybe_new_dt = min(
+        #     deltat_CFL,
+        #     self.deltat_dispersion_relation,
+        #     self.deltat_group_vel,
+        #     self.deltat_phase_vel,
+        #     self.deltat_max,
+        # )
+
+        # Removed phase velocity (considered not relevant)
         maybe_new_dt = min(
             deltat_CFL,
             self.deltat_dispersion_relation,
             self.deltat_group_vel,
-            self.deltat_phase_vel,
             self.deltat_max,
         )
 
+
         if self.params.forcing.enable:
             maybe_new_dt = min(maybe_new_dt, self.deltat_f)