Sph properties

Once !159 (merged) has been merged in, this merge request improves the handling of SPH parameters by actually reading them from the YAML file and not simply using the constants from const.h

examples/CosmoVolume/cosmoVolume.yml

@@ -34,11 +34,12 @@ Snapshots:
 
 # Parameters for the hydrodynamics scheme
 SPH:
-  resolution_eta:        1.2349   # Target smoothing length in units of the mean inter-particle separation (1.2349 == 48Ngbs with the cubic spline kernel).
-  delta_neighbours:      1.       # The tolerance for the targetted number of neighbours.
-  CFL_condition:         0.1      # Courant-Friedrich-Levy condition for time integration.
+  resolution_eta:        1.2348   # Target smoothing length in units of the mean inter-particle separation (1.2348 == 48Ngbs with the cubic spline kernel).
+  delta_neighbours:      0.1      # The tolerance for the targetted number of neighbours.
   max_ghost_iterations:  30       # Maximal number of iterations allowed to converge towards the smoothing length.
   max_smoothing_length:  0.6      # Maximal smoothing length allowed (in internal units).
+  CFL_condition:         0.1      # Courant-Friedrich-Levy condition for time integration.
+  max_volume_change:     2.       # Maximal allowed change of volume over one time-step
 
 # Parameters related to the initial conditions
 InitialConditions: