GUI - Simulate & Reset

Here you can find everything to start, resume, and control a simulation. The two main buttons, “Simulation” and “Reset”, carry small triangles where you can find additional functions and settings. The “Simulation” button's submenu especially contains very important parameters under the “Options…” menu.


With this button you can trigger a simulation. During this process RealFlow performs all of the necessary calculations, generates the data files and writes them to disk. The simulation itself obeys several settings that can either be defined globally with "Preferences" or individually for each scene. For adjusting the settings per scene, simply click on the small triangle to expand a new menu.



With this button you remove all previously simulated data. The orange progress bar in the timeline disappears and everything is reset to the currently saved state. If you have accidentally pressed “Reset”, it is possible to restore the cached simulation data with Alt + U.


Simulation” Context Menu

The small button with a triangle next to “Simulation” contains four entries:




Fluid Dynamics/Object Dynamics

These options switch the appropriate simulation engines off or on. By default, the solvers are activated, but if you disable one of these options you will be asked to confirm your choice.

Command line

RealFlow comes in two flavours: the standard application uses a graphical user interface – a GUI. There you always have visual feedback from simulations and mesh creation, you can adjust the parameters and use the built-in main tools and functions. Another way to open RealFlow is without its GUI. In this case, RealFlow is started from a terminal application, e.g. “bash” or OS X's “Terminal” program. Here, you do not have any control elements and the loaded scene must be completely prepared inside the GUI application and be ready to simulate.

The advantage of this version is that simulations will perform much faster, because RealFlow does not have to spend any CPU time on updating the viewports, drawing the particle positions or displaying hundreds of objects. OS X users will also love this simulation method, because it allows them to simulate with a 64 bit version of RealFlow and use more memory.

You can trigger a simulation directly on RealFlow's “-nogui” version. You do not have to create long terminal strings manually anymore in order to start the process and everything will be done automatically. As long as this option is activated, RealFlow will always send the currently opened project to the terminal. To deactivate this feature, simply click on “Command line” again to remove the tick. For more information about RealFlow's “Command Line” version, please click here.

Command line options...

Please see below for a detailed description of the contained settings and options.


This part is probably of great interest, because there you will find all simulation-related settings. An in-depth explanation of the different parameters can be found in the "Simulation - Options" chapters

Command line options...

With the help of this panel it is possible to configure a command line simulation. The parameters do not have any effect on GUI simulations.


"Range" Section

Same as scene

When this option is checked the command line simulation's range is exactly the same as the one adjusted on the timeline. To specify a new range, disable “Same as scene” and enter your values in the unlocked fields below.

Frame begin/Frame end

If you want to perform a simulation within a specified range only, uncheck “Same as scene” and enter start and stop frames. Please make sure that “Frame begin” is smaller than “Frame end” to get a plausible result. “Frame begin” also needs to be adjusted if you want to resume a simulation from a certain point in time.

"Threads" Section

Same as scene

This option is enabled by default and the number of threads is read from the scene's “Simulation options”. In some cases, for example with very low particle counts, it is often helpful to use only one or two threads to accelerate the simulation. If you disable the checkbox the “Threads” field becomes editable.


To enter a new number of threads you have to disable “Same as scene” first. Then, you can enter a new value.

"Args" Section


With this option enabled, RealFlow will perform a “normal” simulation using the current scene's settings; the simulation performs exactly the same way as if you were executing it inside the GUI version – but faster.


When “Reset” is active, the simulation will be reset before it finally starts. All previously cached data will be overwritten.

Use cache

When this argument is enabled RealFlow will load all available cache files for the start frame (see “Range” field) directly before the simulation starts. This option has to be active if you want to resume from an interrupted simulation. Without "Use cache", the simulation simply starts from the specified frame without reading previously stored data.


If you only want to perform the creation of meshes from already cached data please choose this mode. In this case, the “Command Line” version will not simulate again and already existing files will be kept.

Reset” Context Menu

Next to the “Reset” button, you will find an expansion menu again with “Reset To Initial State”. By activating this option it is possible to read from a previously simulated, and saved, initial state (which can be compared with a preset), and start the simulation using these particular settings.



An example:

RealFlow standard particle fluids always carry a certain amount of energy, making the particles bounce and jitter. This motion can be removed by allowing the particles to settle down. Once the fluid is calm, you can define a certain frame as an initial state and resume from this position without creating an extra scene.

The last element of the simulation controls is the progress bar. During a simulation or a meshing task, RealFlow displays the progress of the current frame in percent, so the range goes from 0 to 100.