Added a growth time for the sine-wave external potential test case.

examples/parameter_example.yml

@@ -107,6 +107,12 @@ DiscPatchPotential:
   timestep_mult:   0.03     # Dimensionless pre-factor for the time-step condition
   growth_time:     5.       # (Optional) Time for the disc to grow to its final size (multiple of the dynamical time)
 
+# Sine Wave potential
+SineWavePotential:
+  amplitude:        10.     # Amplitude of the sine wave (internal units)
+  timestep_limit:   1.      # Time-step dimensionless pre-factor.
+  growth_time:      0.      # (Optional) Time for the potential to grow to its final size.
+ 
 # Parameters related to cooling function  ----------------------------------------------
 
 # Constant du/dt cooling function

src/potential/sine_wave/potential.h

@@ -43,6 +43,9 @@ struct external_potential {
   /*! Amplitude of the sine wave. */
   double amplitude;
 
+  /*! Growth time of the potential. */
+  double growth_time;
+
   /*! Time-step limiting factor. */
   double timestep_limit;
 };
@@ -76,7 +79,13 @@ __attribute__((always_inline)) INLINE static void external_gravity_acceleration(
     double time, const struct external_potential* restrict potential,
     const struct phys_const* restrict phys_const, struct gpart* restrict g) {
 
-  g->a_grav[0] = potential->amplitude * sin(2. * M_PI * g->x[0]) /
+  float Acorr = 1.;
+
+  if (time < potential->growth_time) {
+    Acorr = time / potential->growth_time;
+  }
+
+  g->a_grav[0] = potential->amplitude * Acorr * sin(2. * M_PI * g->x[0]) /
                  phys_const->const_newton_G;
 }
 
@@ -114,6 +123,8 @@ static INLINE void potential_init_backend(
 
   potential->amplitude =
       parser_get_param_double(parameter_file, "SineWavePotential:amplitude");
+  potential->growth_time = parser_get_opt_param_double(
+      parameter_file, "SineWavePotential:growth_time", 0.);
   potential->timestep_limit = parser_get_param_double(
       parameter_file, "SineWavePotential:timestep_limit");
 }