Page Contents


Overview


The Liquid Source controls how fluid is emitted from geometry or particles into the Phoenix FD Simulators. The fluid is emitted from the surfaces or the volumes of the specified objects (emitters). The viewport gizmo does not emit the fluid itself - it is just a container for the parameters.

The Liquid Source interacts by default with all simulators in the scene. If you have many simulators in the scene, you can restrict the source from emitting into certain simulators using the Include/Exclude lists of the Simulators.

Each individual fluid channel includes a Mask slot for modulation with a texture across the surface or the volume of the geometry, and also a checkbox for controlling whether or not the Source will affect the corresponding channel. Also, note that if Emit Mode is set to Volume Brush or Volume Inject, the Map cannot use Explicit Map Channel or Vertex Color Channel mapping, because these apply only for the surface of the geometry.

Additionally, each parameter can have one or many Discharge Modifiers, allowing the emission to change depending on the surface properties for each different voxel of the emitter.

 

Parameters


Emitter Nodes



 

Emitter Nodes | sources – Specifies a list of objects that will emit fluid. Press the Add button and use the Left Mouse Button to select an object in the Viewport or a list of objects using the Scene Explorer.

Can pick Phoenix | pick_ph – When enabled, allows Phoenix FD Simulators to be selected as an emitter in the list above. This usually involves more complicated setups. For additional information, please head over to the Interactions Between Simulators page.

General


Emit Mode ifnotsolid – Specifies the way the objects in the Emitter Nodes emit fluid.

Volume Inject – The volume of the emitters will discharge the selected fluid channels with added pressure. When this mode is selected, the discharge parameter is named Inject Power and it specifies the added volume of the injected fluid per second. This mode is useful for getting explosive discharge. In order to emit from the volumes of objects, this mode requires that all selected emitters are set into non-Solid mode from their Per-Node Properties.

Volume Brush – The fluid inside the volume of the emitters will gradually change towards the selected channel values. When this mode is selected, the discharge parameter is named Brush Effect (%) and it specifies the rate at which the transition takes place. When Brush Effect (%) is 100%, the fluid will immediately reach the selected values, and if Brush Effect (%) is less, it specifies how close the fluid values will get to the values from the source in 1 second. E.g. if the fluid inside an emitter's volume Temperature is 1000 and the Source emits Temperature 2000 with Brush Effect (%) of 80%, then after 1 second the temperature will have risen to 1800. This mode is useful for creating standing volumes of fluid with a high Brush Effect (%), or alternatively - to slowly convert the fluid inside the volume of the emitters to the values selected below over a period of time. In order to affect the volumes of objects, this mode requires that all selected emitters are set into non-Solid mode from their Per-Node Properties.

Surface Force – The surface of the emitters will eject the selected fluid channels along the geometry normals. The fluid's velocity follows the normals of the emitter geometry, so it is important to make sure they are not pointing inwards. When this mode is selected, the discharge parameter is named Outgoing Velocity and it specifies the speed of the emitted fluid in units/sec. The displayed units will change accordingly if the scene units change. This mode can work with emitter objects which are either Solid, or non-Solid in their Per-Node Properties.

When using particles as source geometry, the Surface Force Emit Mode is not supported - Phoenix FD will automatically fall back to Volume Inject mode.

Inject Power / Brush Effect (%) / Outgoing Velocity | discharge / brusheffect / outvel – These parameters control the strength of the source. Check Emit Mode for more info.

Mask | dmap, usedmap Allows you to vary the Outgoing VelocityInject Power or Brush Effect (%) over the surface or the volume of the emitters. White areas of this map will have the strongest discharge, while black areas of the map will not discharge at all. The individual fluid channels can also be modulated using dedicated maps from the options below.

Modifiers |  dmoddisch – Discharge Modifiers can be attached here in order to affect the Outgoing VelocityInject Power or Brush Effect (%) parameters.

Noise | noise – Varies the Outgoing VelocityInject Power and Brush Effect (%) across the surface or the volume of the emitting geometry or particle. The variation also changes over time.

 

Liquid & RGB


 

 

Emit Liquid – Enables or disables liquid emission. Disabling this option is useful in situations where only foam and splashes need to be emitted but not the liquid itself.

RGB | uvw, useuvw – If the RGB Map is not enabled, the emitted fluid's RGB channel will contain the specified color. If the RGB Map is enabled, the RGB values from the texture map will be used instead of the color swatch. If the RGB channel is not enabled in the Output rollout of the Simulator, this parameter will be ignored. Also, note that if Emit Mode is set to Volume Brush or Volume Inject, the Map cannot use Explicit Map Channel or Vertex Color Channel mapping, because these apply only for the surface of the geometry.

Modifiers | dmodrgb – A discharge modifier can be attached here in order to affect the RGB parameter.

Map | uvwmap, useuvwmap – Allows you to vary the RGB over the surface or the volume of the emitters. If this is not used, the Source will emit equal RGB over the entire surface or volume of the emitters.

None – The RGB channel will not vary.
TexMap 
– Allows you to specify a texture map to color the fluid emitted by the Source. If this is used, the color swatch is ignored.
Vertex Color
 – The RGB channel of the emitted fluid is determined by the emitter node's vertex colors.

To render these RGB colors for smoke, set the Smoke Color Based On parameter to RGB. For rendering of meshed liquids, set a Grid Texture as the Diffuse map for a Standard or V-Ray Material, and set the Grid texture's Channel to RGBFor more information, see the RGB Map Vertex Color example below.

 

Particles 



 

Particles | particles, useprt – Allows the source to emit particles into the Simulator. The particle birth rate is in thousands of particles per second.

Type | prttype – Specifies the type of particles created by this source:

Drag – This option is not supported by the Liquid Source. In a Fire/Smoke Simulation, these particles are simply carried by the velocity of the simulation, without interacting with one another. In a Liquid Simulation, a similar behavior is provided by the liquid particles which can be rendered using a Phoenix FD Particle Shader. If necessary, the Count Multiplier setting on the Particle Shader can be used to increase or decrease the density of the particles.
Foam – The source will emit Foam particles. Note that Foam simulation must be enabled from the Simulator so this type of particles can be emitted into it.
Splashes – The source will emit Splash particles. Note that Splash simulation must be enabled from the Simulator so this type of particles can be emitted into it.

Modifiers | dmodprt – A discharge modifier can be attached here in order to affect the Particles parameter.

Mask | prtmap, useprtmap – Allows you to vary the amount of particles over the surface or the volume of the emitters. If this is not used, the Source will emit equal amount of particles over the entire surface or volume of the emitters.

Viscosity




Viscosity viscosity, usevisc – Specifies the viscosity of emitted liquid. If the viscosity channel is not enabled in the Output rollout of the Simulator, this parameter will be ignored.

Modifiers |  dmodvisc – Discharge Modifiers can be attached here in order to affect the Viscosity parameter. The modifier ramp works as a multiplier to the Viscosity value.

Map viscmap, useviscmap – Allows you to vary the viscosity over the surface or the volume of the emitters. If this is not used, the Source will emit equal viscosity over the entire surface or volume of the emitters.

None – The Viscosity channel will not vary.
TexMap 
– Allows you to specify a texture map for the Viscosity channel.
Vertex Color
 – The Viscosity channel of the released fluid is determined by the emitter node's vertex colors. 

Emission



 

Motion Vel. | usevel, velmult – When enabled, moving emitters will affect the velocity of the fluid and make it follow the emitter. This effect is controlled with the specified multiplier. If the emitter is not moving, this option has no effect.

  • Particles with attached geometry (such as PFlow particles using a Shape Instance operator) will act like standard geometry obstacles and will push the fluid by default, as long as their Solid Phoenix property is enabled.
  • Particles without geometry (even PFlow particles with a plain Shape operator) will need to be attached to a Source in order to interact with the fluid in any way.
  • Particles without geometry can emit fluid using their shape and size using the Source's Particle Shape and Custom Prt Size options.
  • Particles without geometry will not affect the fluid's motion by default, so you need to enable Motion Vel. explicitly if you need this effect.
  • If Motion Vel. is enabled, the fluid emitted by a particle may refuse to leave the particle shape area and continue to move together with the particle, because it will have the same velocity.

Polygon ID | poly_id – Only the polygons with the specified ID of the emitter geometry will emit the fluid. This option affects the discharge only in Surface Force mode.

Time Base | timebase – This parameter is used when emitting from particle systems. It allows you to animate the parameters using the age of the particle instead of the timeline frame time.

Absolute – Parameters of the source will be animated based on the timeline frame time.
Particle Age – Parameters of the source will be animated based on the age of the particle. This way, values at timeline frame 0 will apply to each particle at the moment of its birth, and e.g. values at frame 10 will apply to the particle 10 frames after it was born. This allows particles born at different moments to perform identical animations offset in time. This can be useful e.g. if you want all particles to emit strongly after they are born and reduce their emission after a while, but in case the particles are born through a long period of time, the Absolute mode will change the discharge of all particles together, while Particle Age will allow each particle to have its own copy of the animation.

Prt Shape | prt_shape – This parameter is used when emitting from particle systems.

Sphere, 1 voxel – Each particle will be the size of one grid cell. Particle sizes and shapes will be ignored.
Sphere, use size – The particle sizes will be used, but the shape will always be spherical.
Sphere, custom size – The particle shape will be spherical and the size will be taken from the Custom Prt Size field.
Use particle shape – The particle shapes will be used as they are provided. This might slow the simulation down if there are a large number of particles.

When a source emits from non-solid particles in any of the Sphere modes, the simulator traces each moving sphere and emits continuously throughout its trajectory, no matter how fast the particle is moving and how many steps the simulation uses. In a contrary way, in Use particle shape mode, the particles are getting evaluated the same way as regular mesh geometries, so in motion they are sampled only at the simulation steps without filling the trajectory in between the particle positions in time. In such case, if a particle moves very quickly and the simulator has low Steps per Frame, the trajectory of the particle would get interrupted and you should increase the simulation steps in order to keep it continuous.

Custom Prt Size | prtsphsz – Specify a custom size for the particles using this option. The size is in scene units.

 

Example: RGB Map Vertex Color



 

Smoke Simulation
Map = Vertex Color

Liquid Simulation
Map = Vertex Color