--- title: "30 - Fluid & Global Fluid Controls" url: "https://help.maxon.net/rg/en-us/Content/html/30-Form-fluid-global-fluid-controls.html" section_path: "Particles and 3D > Form > 30 - Fluid & Global Fluid Controls" description: "These two sets of parameters control the fluid behavior of particles when Fluid Motion is enabled." --- # 30 - Fluid & Global Fluid Controls Form ### Fluid & Global Fluid Controls These two sets of parameters control the fluid behavior of particles when Fluid Motion is enabled. ![Image: fluidcontrols_trapcode-form.png](https://help.maxon.net/rg/en-us/Content/Resources/Images/fluidcontrols_trapcode-form.png)\ **Fluid** The Fluid model creates a field of buoyant (upward or downward) and vortex (spiral) forces that move particles within your form in a fluid-like manner. Special notes: - When working with 3D models, animated sequences are not supported when working with fluid dynamics. - When Fluid Motion is enabled, the base form position cannot be animated. **Fluid Motion** Toggles whether fluid forces are applied to your particle form. **Fluid Force** Defines what type of force applies to fluid particles - Buoyancy & Swirl Only: Particles receive an upward force akin to buoyancy, as well as a random force applied individually or jointly across all three axes. - Vortex Ring: Particles receive an upward buoyant force, which is centered in a ring comprised of vortex forces that propel particles in a determined direction. - Vortex Tube: Particles receive an upward buoyant force while surrounded by a single vortex force, spinning particles in a cylindrical manner. ![Particle simulation with Fluid Force set to Buoyancy & Swirl Only](https://help.maxon.net/rg/en-us/Content/Resources/Images/Screen-Shot-2018-09-25-at-5.35.51-PM_trapcode-form.png) Buoyancy & Swirl Only ![Particle simulation with Fluid Force set to Vortex Ring](https://help.maxon.net/rg/en-us/Content/Resources/Images/Screen-Shot-2018-09-25-at-5.36.01-PM_trapcode-form.png) Vortex Ring ![Particle simulation with Fluid Force set to Vortex Tube](https://help.maxon.net/rg/en-us/Content/Resources/Images/Screen-Shot-2018-09-25-at-5.36.10-PM_trapcode-form.png) Vortex Tube **Apply Force pop up** Determines if the force dictated above applies continuously or only once at the start of the effect. **Force Lifetime** Defines the timeframe in which fluid forces apply to the particle form. Lower values equal a shorter timeframe and faster motion while higher values create slower forces and slower motion. If Apply Force is set to Continuously, this determines when the forces are regenerated. **Force Relative Position** Determines where, in relation to the base form, the forces defined above are applied to the particles on x, y, and z coordinates. **Force Region Size** Determines the size of the area in which fluid forces are generated. **Buoyancy** Defines how much upward or downward force is applied to the particles. **Random Swirl X, Y, Z** Controls how turbulent swirling forces are applied along particles’ x, y, and z axes. The higher the number, the stronger the forces and the farther the particles travel from their original position. **Swirl Scale** Adjusts the complexity of swirl patterns. Low values provide large swirls while higher values provide smaller swirls. **Random Seed** Adjusts the integer used to create a random effect. Changing this helps give one fluid particle effect a slight variation from others in your composition. **Vortex Strength** Controls the vortex spin speed, which increases and decreases the strength and direction of its force on fluid particles. **Vortex Core Size** ![Image: vortexcoresize_trapcode-form.gif](https://help.maxon.net/rg/en-us/Content/Resources/Images/vortexcoresize_trapcode-form.gif) Adjusts the diameter of the vortex forces used to spin the fluid particles. **Vortex Tilt** ![Image: vortextilt_trapcode-form.gif](https://help.maxon.net/rg/en-us/Content/Resources/Images/vortextilt_trapcode-form.gif) Tilts the vortex forces along the axis of the buoyancy force. **Vortex Rotate** ![Image: vortexrotate_trapcode-form.gif](https://help.maxon.net/rg/en-us/Content/Resources/Images/vortexrotate_trapcode-form.gif) Rotates the vortex forces around the axis of the buoyancy force. *Note that this will only have a noticeable effect when the vortex tilt has been adjusted.* **Visualize Relative Density** Controls particle appearance relative to the combined density of particles and the fluid forces surrounding them: - **Off:** The default setting. Particle appearance is not affected. - **Opacity:** Changing the number of surrounding particles or the strength of fluid forces around them will affect a particle’s opacity. Increased levels make a particle more opaque while decreased levels make it more transparent. - **Brightness:** Changing the number of surrounding particles or the strength of fluid forces around them will affect a particle’s brightness. Increased levels make a particle brighter while decreased levels make it darker. ![Fluid simulation with Visualize Density set to Off](https://help.maxon.net/rg/en-us/Content/Resources/Images/off_trapcode-form.gif) Visualize Density Off [Video: opacityfactor_trapcode-form.mp4](https://help.maxon.net/rg/en-us/Content/Resources/Images/opacityfactor_trapcode-form.mp4) Opacity [Video: lightnessfactor_trapcode-form.mp4](https://help.maxon.net/rg/en-us/Content/Resources/Images/lightnessfactor_trapcode-form.mp4) Lightness **Global Fluid Controls** ![Image: Screen-Shot-2018-09-28-at-4.01.07-PM_trapcode-form.png](https://help.maxon.net/rg/en-us/Content/Resources/Images/Screen-Shot-2018-09-28-at-4.01.07-PM_trapcode-form.png) These controls affect all particle systems within your Form effect that are using the Fluid physics model. **Fluid Time Factor** Controls tthe timeframe in which forces apply to fluid particles. Lower values mean forces apply more slowly while higher values mean they apply faster. Note that this number increases exponentially, so if you're looking for finer controls — consider adjusting this value by the tenths — a shortcut for this is holding down the Alt key while scrubbing the parameter. Alternatively, you can manually enter your values. **Viscosity** Defines how sticky your particles are to one another, creating a semi-fluid or thicker appearance. **Simulation Fidelity** Controls the complexity of the pattern of forces applied to fluid particles. Higher values equal more granular, micro-scale interactions while lower values create broader, macro-scale interactions. ![Fluid simulation with low fidelity](https://help.maxon.net/rg/en-us/Content/Resources/Images/lowfidelity_trapcode-form.gif) Low fidelity ![Fluid simulation with high fidelity](https://help.maxon.net/rg/en-us/Content/Resources/Images/highfidelity_trapcode-form.gif) High fidelity *With high fidelity, the force affects finer areas of the form.*