#Realflow smoke series

Multi-GPU simulations are currently not possible.The вЂњSheeterвЂќ daemon's main purpose is to detect holes in particle fluids and fill them, but without increasing the emitterвЂ™s вЂњResolutionвЂќ value. When 'Use GPU' is active you will see a drop-down menu with all available graphic boards.

For more information visit the в†’В ' GPU-Acceleration' page.

Old and low-performance graphic cards normally do not have any effect on simulation time or might even slow down the simulation.The amount of VRAM determines the size of the simulation and there is currently no fallback on the mainboard's RAM.

#Realflow smoke series

Gaming cards like the GeForce series perform very well with RealFlow | Cinema 4D.

To speed up simulation by 3-8x (depends on your graphic card and CPU) compared to the CPU, enable this feature: If this option is checked, interpolated values between frames are transferred to the simulation. Sometimes emitters and daemons have some of their parameters are animated.

1.0 RealFlow finds a solution that is very close to the exact behaviour, but simulation time will increase.

0.0 RealFlow quickly finds a solution, but it will not be very accurate.

This parameter ranges between 0.0 and 1.0.

For the materials, mentioned above, a fixed number of iterations often works well, e.g.

Iterations are applied per subset, so with substeps value a materials rigidity will also increase.

The higher the values, the more rigid the material will finally be.

These two parameters are important for the rigidity of elastic, granular, viscous, and viscoelastic materials: Substeps should also be increased when you see distorted polygons in conjunction with rigid or elastic particles and the 'Skinner' daemon.

If you see popping particles while the fluid settles try to increase 'Min Iterations' and/or 'Min Substeps'.

if possible, make the collision object thicker.

try do reduce the particles speed with a 'Drag Force' daemon.

enable 'Continous Collision Detection' in the 'Volume' tag.

decrease the object's 'Cell Size' in the 'Volume' tag.

If you see particles going through a solid object Substeps play an important role for collision detection. Here you find the minimum and maximum numbers of simulation steps. This also applies to simulations with collision geometry involved. 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. When enabled, RealFlow | Cinema 4D applies default settings. The default value of 0.5% should work for most parented objects. The value represents a percentage of the distance between every vertex and the center of mass of every object. If the value is too small, some objects that are just animated (or parented) may be considered deformed just because of precision errors, decreasing the simulation performance greatly. However, if the value is too high there might appear differences between the real object and the geometry 'seen' by RealFlow. A bigger value would recompute less often the colliding geometry, thus providing a better performance.

This is the threshold used to consider if an object with a RFCollider is being deformed or just transformed. With вЂњUse Geometry VelocityвЂќ the interaction will happen in time again. Here, RealFlow | Cinema 4D uses very large substeps to speed up the simulation.Дue to these large steps the interaction between the object and the fluid is delayed. Imagine an animated object falling into a container with calm water. When enabled RealFlow | Cinema 4D will adjust the simulation's substepsВ to get a correct fluid-object interaction behaviour:

With values smaller than 1.0, the fluid can cover a longer distance within a single step вЂ“ the solver is less strict.

With a value of 1.0, the fluid will not move more than 1 grid cell in the current simulation step.

RealFlow | Cinema 4D calculates how fast the fluid will move within a simulation step (aka 'time step' or 'substep', see below): вЂњTime scaleвЂќ works as a factor: 2.0 means that the fluid will be two times faster. Values smaller than 1.0 will decelerate the fluid settings greater than 1.0 have an acceleration effect. When this option is checked RealFlow | Cinema 4D will always use the maximum number of threads. Here you specify how many computer processors and cores you want to use with your simulations.