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As you can see in the preview animation, we have unwanted fire in the smoke.

Keep the simulation unchanged. Go to Simulator → Rendering rollout, click on the Volumetric Options, disable the Fire.

We still need to simulate the temperature so it would make the smoke rise up, so we don't disable it from the simulation via the Output rollout, but instead just turn it off for rendering.

Set the Smoke Color to light gray color (RGB = 245, 245, 245). Also, disable the Scattering.

Now the smoke appears too thin, so let's increase the Simple Smoke Opacity to 0.9 (found in the Smoke Opacity rollout).

Our final goal for the simulation is a smooth, natural-swirling, cigarette smoke look. So all of the following steps aim at this goal. Now the smoke appears to be running too fast.

To slow it down, change the Time Scale from 1.0 to 0.7.

Now, let's modulate the Smoke Opacity.

Set the Smoke Opacity to be Based on Simple Smoke.

Enable the Modulate option.

Keep the Noise texture that we used in the previous step and change the following settings:

Set the Size to 0.2;

Noise Threshold High to 0.5, Low to 0.45;

Levels to 2.0.

Now you understand how this technique works and its possible side effects.

Let's adjust the final Noise texture for the texture slot of the Smoke Opacity. The settings for the texture are now optimized in order to minimize the unnatural look of suddenly appearing/disappearing islands of smoke.

Plug in a new Noise texture in the Texture slot.

As shown, set the Noise Type to Turbulence.

Size to 0.1.

Noise Threshold High to 0.8, Low to 0.32.

Levels to 5.0.

Keep the UVW Tiling to 1.0.

For the Coordinates, set Source to Explicit Map Channel. By doing so we can take advantage of Phoenix FD's grid Texture UVW.

The smoke looks quite choppy, but we are going for a smoother look. The noise in the smoke is caused by the Vorticity parameters in the Dynamics rollout of the Simulation. We can resolve this by reducing the Smoke Surface Vorticity to 0.

Go to the Fire/Smoke Simulator and run the simulation again.

To achieve a better swirling motion in the simulation, we can change the conservation mode and increase the Conservation Quality parameter under the Dynamics rollout. Set the Conservation Mode to PCG Symmetric, Quality to 50.

The PCG Symmetric conservation mode is ideal for smoke simulations or explosions because it tends to produce strong conservation which needs less conservation quality in order to look realistic. This method is also used for the Cigarette Smoke quick preset. So we choose this mode.

Go to the Fire/Smoke Simulator, and run the simulation again.

Now, in order to make our animation more interesting, we can animate the Time Scale. This section of the tutorial is optional – you may skip to the Rendering section below.

To create the bullet-time effect, open the Dynamics rollout of the Phoenix FD Simulator and animate the Time Scale parameter as follows:

Frame 0: 0.7
Frame 100: 0.7
Frame 130: 0.3
Frame 145: 0.3
Frame 164: 0.7

The Time Scale is a global multiplier for the dynamics of the Simulator. Reducing it uniformly scales down all sources of velocity in the simulation.

Here we summarized the pros and cons of the two methods.

The technique we demonstrate in this tutorial creates softer and smoother results. The simulation and rendering are very fast compared to the particle-based ones. However, you can get more accurate results when using the cigarette smoke quick preset.

Feel free to use whichever method suits you best for a project.