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Requires Phoenix FD 3.14.00 Official Release and V-Ray NEXT Official Release for Maya 2015 or newer. You can download official Phoenix and V-Ray from https://download.chaos.com. If you notice a major difference between the results shown here and the behavior of your setup, please reach us using the Support Form.

The instructions on this page guide you through the process of creating a Burning Aroma Stick simulation using Phoenix and Maya. At its core, this is a particle simulation driven by the Velocity channel of the Phoenix Simulator. You may know this process as Advection.

The Phoenix Source is capable of emitting not only Smoke, Fuel or Temperature but also particles. We emit Drag particles for this effect - drag particles are, as the name implies, dragged by the Velocity of the simulation. The Drag particles are then rendered with the Phoenix Particle Shader in Point mode, with very low Point Alpha - the combination of a large amount of particles and a high transparency produces the illusion of smoke.

Finally, the simulation is slowed down using the controls in the Input rollout of the Phoenix Simulator.

To download project files:

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Scale is crucial for the behavior of any simulation. The real-world size of the Simulator in units is important for the simulation dynamics. Large-scale simulations appear to move more slowly, while mid-to-small scale simulations have lots of vigorous movement. When you create your Simulator, you must check the Grid rollout where the real-world extents of the Simulator are shown. If the size of the Simulator in the scene cannot be changed, you can cheat the solver into working as if the scale is larger or smaller by changing the Scene Scale option in the Grid rollout.

Go to Windows → Settings and Preferences → Preferences → Settings and set the Working Units to centimeters.

Set the Time to 30fps. We do this to ensure result parity with 3ds Max. You may skip this step if you find it unnecessary. Keep in mind the final result of your simulation may turn out slightly different.

The final scene consists of the following elements:

1. The Vase and Aroma Stick geometry - the very tip of the aroma stick geometry is used to emit drag particles into the Phoenix Simulator. This is achieved using the Emit Material option on the Phoenix Source.
2. Phoenix Simulator - the simulator is used to generate the Velocity Grid channel used to advect the Drag particles.
3. Phoenix Source - the source emits Smoke, Temperature and Drag particles into the simulation.
4. Phoenix Turbulence - the turbulence is used to add subtle detail to the final simulation.
5. Phoenix Particle Shader - used to render the Drag particles in Point mode, with very low Alpha.
6. V-Ray Dome Light - an environment light with an HDRI is used to light and render the final scene.
7. Camera - for the final render.

Start by opening the .ma file.

The provided file contains the Vase and the Aroma Stick geometries.

The material for the vase is completely refractive so the geometry may not be immediately visible in the Viewport in case Shaded Display (hotkey 5) is enabled.

To the right is a Playblast of the simulation in its current state.

Select the Phoenix Source and enable the emission of Particles under the Fluid Discharge rollout, with a value of 250.

Set the Particles Type to Drag, with a Lifespan of 2.5 seconds and a Lifespan Variation of 0.5 seconds.

Enable Export Drag Particle IDs - the particle ID channel is required when slowing down a simulation. Later in the tutorial, we use the controls on the Phoenix Simulator → Input rollout to slow the simulation down to half its speed.

Additionally, if you want to render the drag particles with motion blur, you also need to enable output of Drag Particle Velocity from the Source.

To the right is a Playblast of the simulation in its current state.

As you can see, the movement of the Drag particles closely resembles the movement of the Smoke from the previous Playblast. Here is a simple explanation for this - both the Smoke and the Drag particles are carried by the exact same Velocity channel. You could achieve the exact same 'thin smoke' effect with Smoke instead of Drag particles – this would require a much higher grid resolution, and consequently would take much longer to simulate.

The chaotic movement is caused by the default Vorticity settings - those work great for regular smoke simulations but in this cause, the additional randomness is working against the effect we are trying to achieve.

Select the Phoenix Simulator and go to the Dynamics rollout.

Under Vorticity, disable Massive Vorticity and set Classic Vorticity to 0.

For in-depth information on the Vorticity types, please check the Vorticity documentation.

To the right is a Playblast of the simulation in its current state.

Disabling the Vorticity slightly reduced the amount of randomness in the simulation. However, the simulation is still too turbulent for the type of effect we're trying to create.

Select the Phoenix Source and reduce the Discharge to 1. This will scale down the Smoke and Temperature pumped into the simulation.

Under the Phoenix Simulator → Dynamics rollout, set the Steps Per Frame to 5.

The SPF parameter has the 'side effect' of calming fluid simulations - more steps generally produces smoother movement. If you are creating an explosion, it would be best to keep this value as low as possible. For smooth, slow-moving simulations, higher values will yield better results.

To the right is a Playblast of the simulation in its current state.

Increasing the SPF gives the Drag particles a much smoother Velocity field to travel on, and as a consequence - they've started nicely clumping up.

You could experiment by increasing the SPF even higher - for this example, we keep the SPF at 5.

Aroma Sticks (and also cigarettes, in case you're going for a cigarette smoke simulation) do not emit smoke from their entire surface. An easy way to limit the emission of particles to a subset of faces on the emission geometry is to use an Emit material.

Select the second row of faces starting from the top of the aromaStick_01 geometry and use the Right Mouse Button → Assign New Material option to give them a new Lambert material.

Rename the new material to mtl_emit_01 and specify it under the Phoenix Source's Emit Material parameter.

Select the aromaStick_01 geometry and open the Attribute Editor. Under the aromaStick_Shape1 node → Extra Phoenix FD Attributes, set the Voxel Mode Override to Inscirbed.

This option overrides the Simulator → Scene Interaction → Object Voxels parameter. It controls the way the geometry is represented inside the Phoenix simulation. You can think of this as the thickness of the walls of the aroma stick.

We reduce this value to make sure the particles are emitted as close to the surface of the geometry as possible.

Go to the Phoenix Menu → Create → Turbulence.

Set the Strength to 1, with a Size of 15 and Rate of Change of 0. Those settings are purely an artistic choice - feel free to experiment with them to find a look you enjoy.

Hit Simulation → Start to cache the simulation to disk.

Under the Phoenix Simulator → Input rollout , set the Play Speed to 0.5 to slow the simulation down to half its speed.

If you encounter any errors, or the particles do not seem to blend smoothly from frame to frame, make sure that the Export Drag Particle IDs on the Phoenix Source is Enabled.

To the right is a Playblast of the final simulation.

In the next section, we create the Phoenix Particle Shader used to render the Drag particles.

Phoenix ships with a custom Particle Shader which can be used to quickly render any particle system placed into its Particle Set.

To create one, go to Phoenix FD Menu → Create → Particle Shader. Note that a new set has appeared in the Outliner – phxParticle_set. This set is automatically generated for each Phoenix Particle Shader in the scene, and used to tell the shader which particle systems in the scene are to be rendered.

Open the Windows → Relationship Editors → Sets and select phxParticle_set1 on the left, and PG_PhoenixFDSimulator1_* on the right. The nodes prefixed with PG are Phoenix Particle Groups - those nodes reference the particle systems generated by the Phoenix simulation. By adding it to the Particle Shader's Particle Systems set, we tell Phoenix to render the Drag particles. This works exactly the same for Foam, Splash and Mist particles when rendering Liquid simulations.

To the right is a rendered image of the current setup. As you can see, the particles appear too thick.

Select the Particle Shader and set the Color to RGB: [ 204, 204, 204 ].

Open the Point rollout and set the Point Alpha to 0.001, the Point Size to 0.700 and the Shadow Strength to 0.01.

Those values are purely an artistic choice - feel free to modify them as you see fit.