Simulation |
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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.
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
Object voxels(MXS: objvox) - Each solid object is represented in the grid as voxels. This options chooses how to proceed when given voxel intersects the object's surface i.e. is particularly in the object. It does not produce significant change in the simulation, but is of crucial importance for the rendering. For example, if the object voxels are circumscribed, the liquids can't reach the real objects surface and this is visible in the rendering. This option has a per object form, you have to define an user defined property with name PHX_Voxels. The corresponding values are 0 - circumscribed, 1- center, 2 - inscribed.
Circumscribed - all the voxels that have intersection with the surface are considered solid. It's recommended for fire simulations.
Center - the surface voxels are considered solid only if their bigger part lies in the object.
Inscribed - all the voxels that have intersection with the surface are considered non solid. It's recommended for liquid simulations.
Conservation
For detailed explanation of the conservation meaning see the simulation workflow.
Method(MXS: refltype) - choose between different methods for evaluating the conservation.
Symmetric - this method is suitable for simulations which require a high degree of symmetry e.g. a nuclear mushroom.
Smooth - This is the strongest conservation method, it is recommended for liquids and also for simulations where the pressure has an important role.
Buffered - this method is suitable for fire and smoke. Produces more fine details compared to the other methods. Can't be used for liquids.
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| Smoke simulated with symmetric type of conservation | Smoke Simulated with smooth type of conservation | Smoke simulation with buffered type of conservation |
Quality (MXS: reflprec) - This parameter controls how many conservation cycles per single simulation step to be applied. For liquid simulations, the recommended value of this parameter is 20 or more.
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.
Material transfer (Advection)
For detailed explanation of the advection meaning see the simulation workflow.
The advection is closely related to one very important parameter of the simulation - the SPF, and because of this the control over the SPF is also placed in this section.
Method(MXS: advtype) - specifies the algorithm used for calculating the advection
Classic(Semi-Lagrangian) - this is the most commonly used algorithm for advection. Has good stability , the only method that can achieve settled liquids, but does not strictly conserve the quantity of the transferred material.
Slow moving - this method is a modification of the Semi-Lagrangian method optimized for slow moving fluids and preventing the numerical dissipation.
Forward transfer - good conservation abilities, but less stability compared to the classic method. Tends to produce cross-like artifacts when used with liquids.
Maximal step (MXS: adv_step) -
This parameter is used in the automatic SPF adjustment. Advection step X means that in one simulation cycle the fastest point in the fluid will be moved at distance X cells. Bigger advection step produces lower SPF value.
(Steps Per Frame) SPF upper limit (MXS: spflimit1) - If the value calculated in the automatic SPF adjustment is above this value, it is ignored and this value is set as SPF.
(Steps Per Frame) SPF lower limit (MXS: spflimit0) - If the value calculated in the automatic SPF adjustment is below this value, it is ignored and this value is set as SPF.
| SPF=1 | SPF=1.5 | SPF=2 |
Actions
(MXS: A_StartSim,
A_StopSim) -
Start, pause and stop the simulation.
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If the velocity channel is exported, Phoenix is able to restore the simulation. This command finds the nearest file containing velocity channel behind the time slider and continues the simulation from it (see Backup interval parameter)
Load (MXS:A_StartSim) Loads the content of a chosen cache file as initial state for the simulation.
