Simulation Options: Hybrido

Owned by thomas (Unlicensed)
Last updated: 28 Jul, 2015 by Alex Ribao
3 min read

RealFlow's scene-related simulation options are located here:




To change the parameters of this tab on a global level use the → "Preferences - Simulation: Hybrido" dialogue.



Stepping (A: Liquid – Hybrido Solver)

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.

MIN substeps

Specify the minimum number of simulation steps for → HyFLIP fluids:

  • Higher values increase simulation time, but also avoid instabilities.
  • For a fixed number of substeps use equal values for “MIN substeps” and “MAX substeps”.
MAX substeps

Specify the maximum number of simulation steps for → HyFLIP fluids:

  • Higher values increase simulation time, but also avoid instabilities.
  • For a fixed number of substeps use equal values for “MIN substeps” and “MAX substeps”.

 

Please be careful! Let's assume you have the following settings:

  • MAX substeps (General: Stepping) = 1
  • MAX substeps (Hybrido: Liquid – Hybrido Solver) = 3
  • In this case, a substeps value of 1 is used for the HyFLIP simulation.
Strictness

With a value of

  • 1.0 the fluid will not move more than one grid cell in the current time step.
  • smaller than 1.0 the fluid can cover a longer distance within a single step – the solver is less strict.

Transport (A: Liquid – Hybrido Solver)

Particle steps

This parameter defines the number of steps the solver uses to move the particles through the grid cells. Higher values increase the fluid's quality, but the default setting is sufficient in most cases.

Pressure Solver and Viscosity Solver (A: Liquid – Hybrido Solver)

Pressure | Viscosity Solver > MAX iterations

In most cases, the default setting is sufficient, but if you see a warning message in RealFlow's → “Messages” window you should consider a higher value.

Pressure | Viscosity Solver > Accuracy

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.

Collision Fractions Computation Mode (A: Liquid - Hybrido Solver)

These settings influence fluid-object collisions.

Face area

This the fastest method and can be used in most situations:

  • Face area” does not add artificial friction to the fluid – the fluid's behaviour is not affected.
  • If the collision objects are mainly sharp-edged or spiky please consider using “Supersampling”.
Supersampling

If you see collision problems which cannot be solved with an object's → “Volume” setting you might want to use this method instead of “Face area”. This option

  • is very accurate, but also computationally intense and adds some artificial friction to the fluid
  • should not be used with curved objects, because you might see an alias effect in areas where the fluid touches the object's surface
  • is a good choice if collision objects show many sharp angles.
Samples

This is the “Supersampling” option's accuracy. When “Samples” is set to 3 then the total number of samples will be 3 x 3 x 3 = 27.

OpenCL (A: Liquid - Hybrido Solver)

Due to the almost infinite number of hardware combinations we cannot guarantee that RealFlow's OpenCL features are available for any computer or graphic device.

Use OpenCL-CPU

This option is only available if your computer supports OpenGL-CPU calculations.

Use OpenCL-GPU

You can activate this option if your graphics card has OpenCL capability, otherwise it is greyed out. The speed boost is limited and comparable to one additional CPU/core.

Use OpenCL-Accelerator

This function is only available with dedicated OpenCL-acceleration hardware. These devices have to be purchased separately.

System Information

Open a comprehensive summary about your GPU's features and capabilities.

Stepping (B: Liquid - Particles Solver)

MIN substeps

Specify the minimum number of simulation steps for → HySPH secondary fluids:

  • Higher values increase simulation time, but also avoid instabilities.
  • For a fixed number of substeps use equal values for “MIN substeps” and “MAX substeps”.
MAX substeps

Specify the maximum number of simulation steps for → HySPH secondary fluids:

  • Higher values increase simulation time, but also avoid instabilities.
  • For a fixed number of substeps use equal values for “MIN substeps” and “MAX substeps”.