This scheme very closely follows the paper by Wadsley et al. (2017). It includes a “Geometric Density Average Force” equation of motion, explicit corrections for gradients, a Cullen & Dehnen (2010) style artificial viscosity and switch, and an artificial conduction scheme based on the local shear tensor.
The equation of motion:
For more information, please see the Wadsley et al. (2017) paper. Note that we do not use the exact same time-stepping condition, but instead use the same as the other schemes in SWIFT.
To configure with this scheme, use
./configure --with-hydro=gasoline --with-kernel=wendland-C4 --disable-hand-vec
The parameters available for this scheme, and their defaults, are:
SPH: viscosity_alpha: 0.1 # Initial value for the alpha viscosity viscosity_length: 0.2 # Viscosity decay length (in terms of sound-crossing time) # These are enforced each time-step viscosity_alpha_max: 2.0 # Maximal allowed value for the viscosity alpha viscosity_alpha_min: 0.0 # Minimal allowed value for the viscosity alpha diffusion_coefficient: 0.03 # Controls the diffusion rate
There is also a compile-time parameter,
viscosity_beta that we set to
3.0. During feedback events, the viscosity is set to the compile-time
hydro_props_default_viscosity_alpha_feedback_reset = 2.0 and the
diffusion is set to
0.0. These can be changed in