General

Parameters

General

The Simulator is the main component of Phoenix plug-in. It carries out the physical simulation and the rendering. The Simulation rollout holds the settings for the simulation process. It can be found in "Phoenix objects" category of geometry components.

Parameters

Simulator Panel


Threads limit (MXS: maxthreads) - allows you to specify an upper limit for the number of threads used for the simulation. When the value is set to "0" the maximum number of threads(cores) will be used.

 

Start frame (MXS: startframe) - Start frame of the simulation

 

Stop frame (MXS: stopframe) - End frame of the simulation

 

Use script (MXS: script, use_script) - Enables using the MAXScript during the simulation

 

Conservation

 

Method(MXS: refltype) - chose between three different methods for evaluating the conservation.

 

Symmetric - this method is suitable for processes which require a high degree of symmetry i.e. a nuclear mushroom

 

Smooth - this method is suitable for simulations where the pressure has an important role i.e. a pool of water.

 

Bidirectional - this method combines some of the advantages of the previous two methods in a lower degree. Note: this method is not always stable.

 

Quality (MXS: reflprec) - For very advanced users only. It affects the precision of the simulation, and controls the iterations performed when the conservation laws (mass, energy and momentum) are applied.

 

Multithreaded(MXS: mtrefl) - Allows performing the conservation in multithreaded mode. This option is separate from the general Threads limit parameter because if there are some background tasks running, the multithreaded conservation can lead to a very slow performance.

 

Uniform density (MXS: uniform_mass) - controls whether or not the mass of the fluid will be considered during the simulation. The effect of the mass is considered when this box is not checked.

 

Advection

 

Method(MXS: advtype) - specifies the algorithm used for calculating the advection

 

Classic(Semi-Lagrangian) - this is the most commonly used algorithm for advection.

 

Slow moving - this method is a modification of the Semi-Lagrangian method optimized for slow moving fluids and preventing the numerical dissipation.

 

Forward transfer - this method is recommended for simulation of liquids however it can be used for gaseous simulations too.


Maximal step (MXS: adv_step) - Advection is the transporting of quantities according to velocity field. Advection step X means that the fastest point in the fluid will be moved at distance X cells. Bigger advection step increases the turbulence, lower advection step increases the diffusion.

(Steps Per Frame) SPF upper limit (MXS: spflimit1) - This parameter is the "safety valve" of the core. When the simulation leads to very big velocities in some part of the grid (for example a source closed in cavity) it can freeze due to the advection step parameter. In this case the SPF limit will be reached and the advection step will be ignored.

(Steps Per Frame) SPF lower limit (MXS: spflimit0) - When a slow process is simulated (like big nuclear mushroom cloud) the optimal time step can exceed the frame duration. If the time step is limited to the frame duration the fluid's motion will decrease too fast due to the undesired diffusion. On other hand all the updates of the rigid bodies, simulation's parameters etc. are done once per simulation step and can happen to wait few frames until next update. This parameter allows the user to balance between these conflicting situations and to achieve good simulation of slow fluids.

Start, Pause, Stop (MXS: A_StartSim, A_StopSim) - Start, pause and stop the simulation.

Restore (MXS: ) - When the simulation is running the Phoenix regularly saves it's internal state into backup files. This command finds the nearest backup file behind the time slider and continues the simulation from it (see Backup interval parameter)