Inflow Object Settings
Inflow objects emit fluid into the domain continuously. The emission can be set to start or stop by keyframing the Inflow Enabled option. For objects that emit fluid just once, use a Fluid Object.
Need help with how to create simulation objects? Take a look at our getting started guide: Creating Your First FLIP Fluids Simulation.
Video Guide: FLIP Fluids Guide Episode 2B: Inflow and Outflow objects.
Inflow object settings can be viewed in the Physics Properties by selecting the object.
- Inflow objects are required to be Blender mesh type objects.
- Object geometry is required to be Manifold/Closed/Watertight in order to work correctly and predictably within the FLIP Fluids simulator. The objects are required to have volume and planar surfaces cannot be used.
- The object should be sufficiently large/thick in order to be resolved on the simulation grid. The smallest/thinnest geometry features of the object should cover at least one voxel on the simulation grid (What is the simulation grid?).
- If the object is animated, the mesh geometry must not change topology between frames if the Add Object Velocity to Inflow option is enabled. This means that each frame of the animation must have the same number of vertices and triangles and that the vertices are always connected to the same neighboring vertices.
- If the object animation is more complex than keyframed location/rotation/scale, enabling the Export Animation Mesh option will be required.
| Enabled | Whether the object is active and emitting fluid into the simulation domain. Tip: keyframe this option on/off to start and stop inflow emission. |
| Substep Emissions | Number of times fluid is emitted from the inflow per simulation substep. Increase to reduce stuttering fluid artifacts with fast moving keyframed/animated inflow objects. Larger values can increase simulation time and values in the range of 1 to 8 are usually sufficient. If set to 0, the inflow will only emit on the first substep of a frame (What are substeps?). Notes: This option will only have an effect on keyframe/animated inflow objects (except in cases where the value is set to 0). to reduce stuttering for static inflows, increase the simulation minimum substeps value instead. Alternatively, a different choice of inflow shape may be able to prevent stuttering in some cases (See topic in getting started guide). |
| Priority Level | Priority that this fluid object is added to the simulation during a frame. If multiple fluid/inflow objects are adding fluid to the simulation during a frame, the object with the higher priority value will be added first. Use to control which velocity or fluid attributes are prioritized and set first such as with intersecting objects or nested objects. |
| Inflow Velocity Mode | The method in which the velocity of the emitted fluid will be set. Manual Set the inflow velocity vector manually. Axis Set the inflow velocity in the direction of the object's local X, Y, or Z axis. Note: Animations controlled by an armature may not update the object local X/Y/Z axis as expected. If this is the case, an empty object should be parented to a bone and the inflow Target mode set to the empty should be used instead. Target Set the inflow velocity vector towards a target object. |
| Inflow Velocity | The inflow velocity vector (in m/s). This setting is only available if the Inflow Velocity Mode is set to Manual. |
| Inflow Speed | The inflow fluid speed towards the target object (in m/s). This setting is only available if the Inflow Velocity Mode is set to Axis or Target. |
| Target Object | The target object that will be used to calculate the fluid velocity direction.
This setting is only available if the Inflow Velocity Mode is set to Target. Notes: Target objects may be located outside of the simulation domain. Empty objects may be used as target objects. If the target object has non-zero size, the fluid velocity will be directed towards the center of the target bounding box. |
| Export Animated Target | Export the target object mesh as an animated one. This setting is only available if the Inflow Velocity Mode is set to Target. TIP: Animated objects can be slower to export, so use this option only if necessary, such as for armatures or parented objects. Objects with keyframed position/rotation/scale do not require this option to be enabled. |
| Add Object Velocity to Inflow | Add the object velocity to the inflow fluid velocity. |
| Object Velocity Influence | Amount of velocity that is added to the inflow fluid. A value of 1.0 is normal, less than 1.0 will dampen the velocity, greater than 1.0 will exaggerate the velocity, negative values will reverse velocity direction. This setting is only available if the Add Object Velocity to Inflow setting is enabled. |
| Mesh Type | Type of mesh used for the inflow object. Used for calculating object velocities. This setting is only available if the Add Object Velocity to Inflow setting is enabled. Rigid Mesh shape does not change/deform during the animation. Deformable Mesh shape changes/deforms during the animation. Slower to calculate, only use if really necessary. |
| Constrain Fluid Velocity | Force fluid inside of the inflow to match the inflow emission velocity. Enabling this option will allow an inflow to push around fluid when submerged and can also be used to fill up a tank when submerged. Setting low fluid velocity values will have the effect of slowing down fluid emission. See additional notes for applications of this setting. |
Assign attribute values to the fluid generated by this object.
These features are currently affected by a bug in Blender and are hidden by default. Unhide these features by enabling the Developer Tools option in the addon preferences. See the Preferences > Developer Tools documentation for more information on how to enable this feature, the features affected by this bug, and how to work around this issue.
Related Topics
- Domain Attributes Documentation
- Variable Viscosity Documentation
- FLIP Fluids Mixbox Color Blending Plugin
| Color Attribute | Assign this color to the fluid generated by this object. After baking, the color attribute values can be accessed in an Attribute Node with the name flip_color from the Color output. This can be used to create multi-color liquid effects. This attribute can be enabled in the Domain > FLIP Fluid Surface panel or if a domain already exists, by using the operator to the right of this setting. |
| Viscosity Attribute | Assign this viscosity to the fluid generated by this object. After baking, the viscosity attribute values can be accessed in an Attribute Node with the name flip_viscosity from the Fac output. This can be used to create variable viscosity liquid effects. The variable viscosity feature can be enabled in the Domain > FLIP Fluid World > Viscosity panel or if a domain already exists, by using the operator to the right of this setting. |
| Source ID | Assign this ID value to the fluid generated by this object. After baking, the source ID attribute values can be accessed in an Attribute Node with the name flip_source_id from the Fac output. This can be used to create basic multi-material liquid effects. This attribute can be enabled in the Domain > FLIP Fluid Surface panel or if a domain already exists, by using the operator to the right of this setting. Note: This feature is deprecated and will be eventually removed and replaced to expand its functionality and use cases. |
In the first stage of simulation baking, the addon will begin by exporting all object geometry for the animation. These settings allow for control on how and if the geometry should be exported. These settings are only applicable to the object's mesh geometry and do not apply to the object's options and parameters.
| Export Animated Mesh | Export the inflow object mesh as an animated one. TIP: Animated objects can be slower to export, so use this option only if necessary, such as for armatures or parented objects. Objects with keyframed position/rotation/scale do not require this option to be enabled. |
| Skip re-export | If enabled, the addon will skip re-exporting this mesh when starting or resuming a bake. If this mesh has not been exported or is missing files, the addon will automatically export the required files. Notes: Animated mesh export can slow down the export stage if the mesh is complex and contains a lot of geometry. Skipping mesh export for animated meshes will speed up export and help your simulation start quicker. If your animated mesh geometry or motion has changed, you will need to disable this option or force the object to export so that the addon will re-export the mesh geometry. |
| Force Re-Export On Next Bake | When enabled, this option will force the addon to re-export the object’s mesh data the next time that the user bakes or resumes the simulation. This option overrides the Skip Re-Export option. After the object has been re-exported, the force export option will be automatically disabled so that subsequent bakes will continue skipping the mesh for export. This option is only applicable if the Skip Re-Export option is enabled. TIP: Useful for if you have a complex animation or object with a lot of geometry with the Skip Re-Export option enabled to save time during export. Use this option if you make an change to your mesh geometry and want to easily mark the object to update the next time you bake/resume the simulation. |
This operator will copy the Inflow settings of the active object (highlighted object) to all other selected FLIP objects of the same type. Hint: The settings displayed in this UI panel will be the settings of the active FLIP object.
Notes:
- Keyframed settings will not be copied - these will need to be copied manually, such as through the Blender graph editor.
- Settings cannot be copied to an object that has not already been set as an Inflow type object. You will first need to set non-FLIP objects to a FLIP type. Tip: to set multiple objects to a FLIP object quickly, use the FLIP Fluids sidebar > Add Objects operators.