Scene : Global

Owned by thomas (Unlicensed)
Last updated: 08 May, 2018
3 min read

This is the place where the simulation preferences are defined.

 

 

Number of Threads

Here you specify how many computer processors and cores you want to use with your simulations.

Time Scale

Values smaller than 1.0 will decelerate the fluid; settings greater than 1.0 have an acceleration effect. “Time scale” works as a factor: 2.0 means that the fluid will be two times faster.

Stepping Strictness

RealFlow | Maya calculates how fast the fluid will move within a simulation step (aka "time step" or "substep", see below):

  • With a value of 1.0, the fluid will not move more than 1 grid cell in the current simulation step.
  • With values smaller than 1.0, the fluid can cover a longer distance within a single step – the solver is less strict.
Use Geometry Velocity

When enabled RealFlow | Maya will adjust the simulation's substeps to get a correct fluid-object interaction behaviour:

  • Imagine an animated object falling into a container with calm water.

  • Here, RealFlow | Maya uses very large substeps to speed up the simulation.

  • Due to these large steps the interaction between the object and the fluid is delayed.

  • With “Use Geometry Velocity” the interaction will happen in time again.

Auto Params

When enabled, RealFlow | Maya applies default settings. These default values work for most projects with PDB or SPH fluids, but for other materials (granular, viscous, etc.) it is normally necessary to apply custom settings. This also applies to simulations with collision geometry involved.

Min | Max Substeps

Here you find the minimum and maximum numbers of simulation steps. Substeps play an important role for collision detection. If you see particles going through a solid object

  • decrease the object's "Cell Size" in the "Volume" tag
  • enable "Continous Collision Detection" in the "Volume" tag
  • try do reduce the particles speed with a "Drag Force" daemon
  • if possible, make the collision object thicker.
  • If you see popping particles while the fluid settles try to increase "Min Iterations" and/or "Min Substeps".

Substeps should also be increased when you see distorted polygons in conjunction with rigid or elastic particles and the "Skinner" daemon.

Min | Max Iterations

These two parameters are important for the rigidity of elastic, granular, viscous, and viscoelastic materials, but they also help to avoid "popping" particles when fluids/materials interact with objects:

  • The higher the values, the more rigid the material will finally be.
  • Iterations are applied per subset, so with substeps value a materials rigidity will also increase.
  • The → "Damping" parameter influences a materials rigidity as well and the final number of substeps is substeps * iterations * damping
  • For the materials, mentioned above, a fixed number of iteration often works well, e.g. 20 | 20 or 40 | 40.
  • If you see popping particles while the fluid settles try to increase "Min Iterations" and/or "Min Substeps".
Accuracy

In most cases this value can be kept. This parameter ranges between 0.0 and 1.0. With

  • 0.0 RealFlow quickly finds a solution, but it will not be very accurate
  • 1.0 RealFlow finds a solution that is very close to the exact behaviour, but simulation time will increase.