Simulation - Options

RealFlow is a simulation software that provides a wide variety of different so-called solvers. A solver is a program (or a part of it) that can handle complex equations and can be seen as the program's core, because it calculates solutions for the dependencies between this system of equations. RealFlow's parameters can be used to create different starting conditions and therefore, different solutions of the system. Solvers are mainly used for mathematical models or computer simulations to visualize processes. A very important factor with these simulations is time, because, only with the progression of time, is it possible to see the resulting changes and/or dynamics of the examined system.

In computer simulations, time cannot be seen as continuum, but must be subdivided into greater or fewer large steps. The more steps, the better the simulation's “resolution” and the better the final output, but at the cost of simulation speed. Time steps are also responsible for a simulation's stability – one of the main problems with all solvers. During a time step (in RealFlow time steps are also called substeps), the solver calculates the force, acceleration, velocity and finally the position of an object – whether it is a a particle, a rigid body or any other node that contributes to the simulation. The entirety of time steps per frame results in a visible motion that is displayed in RealFlow's viewport. When all frames are assembled together, we can see the dynamics of the object or fluid and its behaviour over time.

Today, there are solvers that work with rather large time steps. RealFlow's Hybrido 2 solver is one of them and it produces very stable and accurate results.

These dependencies between time and the involved properties (forces, velocities etc.) are crucial for simulations and strongly affect the final output. Therefore it is very important to correctly adjust the simulation parameters and choose, for example, an adequate number of substeps.

The “heart and soul” of RealFlow's time and simulation management are the "Simulation Preferences" and the “Simulation Options” panels. Here you can adjust and configure the different solvers to change accuracy, stability and the global interplay of the different solvers.

The timeline, and its associated features, on the other hand, provide convenient functions to control the output of a simulation. You can go through a simulation or animation frame by frame, play back the entire sequence or specify ranges. Two progress bars always keep you informed of the current state of the simulation. A timecode in the viewport shows you additional times (TC = timecode, F = frame, ST = simulation time). It is also possible to adjust the simulation's frame rate to your needs to create slow-motion or time-lapse effects. If you have to deal with variable frame rates, RealFlow's “Simulation Retime” provides very powerful functions to synchronize a simulation with the source footage.

Here is how to access RealFlow's "(Simulation) Options":