Let's see how to set the scene. It contains four Fire/Smoke Simulators: 

Only the PhoenixFDFire-Nuke Simulator and the PhoenixFDFire-Cloud Simulator are actually running the simulation. The other two just have their Volumetric Options tweaked, with no simulation involved.

Let's try to match the real explosion as close as possible. The end result of the simulation fireball is around 520 meters in diameter, which is very close to the size in a reference image.

The nuke explosion serves as a light source in the scene. I don't add any other lights to the environment.

The Wilson cloud is the main effect we’re trying to reach here. So, how exactly to make it work? I add three Tube geometries to the scene and place them above the fireball. The size of the tubes changes over time and is carefully positioned. These tubes act as Fire/Smoke Sources. Their emission mode is set to Volume Brush. Let's calculate the timing when animating the Volume Brush of each Source (PHXSource-Tube01~03) so that the rings form as if they naturally and sequentially show up at the top of the fireball.

The demonstrated method here is not physically accurate but shows how powerful and artist-friendly Chaos Phoenix is.

he screenshot above shows an animation curve for the PHXSource-Tube01~03’s Brush Effect. This parameter is animated, so that the biggest tube gradually brushes out smoke, then a few frames later, the middle-size tube brushes out smoke. Finally, the smallest tube brushes out smoke. Through such manipulation, the effect of naturally forming water evaporation around the heat of a nuclear explosion can be mimicked.
As for the main explosion, the setup is very straightforward. Two Geospheres are used as emitters in the PHXSource-Nuke Source. The diameter of the bigger geosphere is 60 meters.

From frame 0 to frame 19, the two Source parameters (Temperature and Inject Power) are animated, so that the hot temperature is Volume Injected, starting from 3000.0 kelvin, and dropping to 300.0 kelvin over time. (Note that, a nuclear explosion can release roughly around 100,000,273 kelvin of heat. The temperature set here is not physically accurate. The temperature here is in the range of 3000.0 so that we can re-use the Volumetric Settings – the Gradient Ramp and the Curve, that are well established in previous explosion setups.) 

Let's simulate the nuclear explosion with the condensation rings together. Below are the settings for the PhoenixFDFire-Nuke Simulator:

The first thing you’ll notice is the Scene Scale. Lower it down so that the explosion can rise quickly, without giving the source a super high temperature value or smoke buoyancy. For a symmetric mushroom-like explosion, set the Fluidity Method to Direct Symmetric with a Quality of 80. Set the Randomize Amount to 0.1 to introduce some randomness to the simulation. The Steps Per Frame option is set to 2 (you can leave it at 1, but the mushroom cloud rises slightly faster when SPF=2).

Above are the Volumetric Options for the PhoenixFDFire-Nuke Simulator. With the Color Gradient combined with an S-shaped Curve, we can retain most of the details at a higher temperature, avoiding color washout in the explosion shading. These Volumetric Settings are suitable for most types of explosions in general.

The cloudscape is based on the cloud scene from the official tutorial - Animated Clouds. Follow the tutorial for more detailed, step-by-step instructions. Here the “cloud” is emitted  from multiple planes instead of one plane. Let's use the Scatter Compound object in 3ds Max, distributing a plane over another bigger plane. The random rotation and size options allow scattering of the planes quickly. Then set this scatter object as a source. (Standard procedure is the following: set a Shell modified plane and let it emit fluid from one side of its face to ensure the geometry is voxelized correctly. Here we skip the step since we don’t encounter such a problem.)

With the 3ds Max’s Compound-Scatter tool we can scatter a small plane over another bigger plane. The result consists of random Z rotation and Scaling in 168 duplicates of a plane, ready for cloud emission. The compound object allows more flexibility. If we need more clouds, we can simply dial up the Duplicates.

When the PhoenixFDFire-fog Simulator is added in the scene, we start to see some nice light scattering around the fireball. However, the lower part of the image, where the cloudscape resides, appears too clear. It should be foggier in that area.

Let's add another layer of fog called PhoenixFDFire-fog-lower that covers the lower part of the scene. This makes the cloudscape more convincing.

By Hammer Chen, Kristin Ivanova

Final animation

Here I modeled a solid geometry for a car with many parts. It contains all the essential components for a typical car from exterior to interior. You can replace those low-poly gears with high poly in real production.

The car interior is basic. It's needed only so when it explodes, to have something burning on the inside. 

The car dynamics are constructed by using tP joints helper in combination with the ShapeCollision operator. For example, for the front left wheel, it is constrained by using a TP Joint SC Helper, type set to Spring. The strength of the car suspension can be controlled through Spring, Damping, and Friction parameters.

Let's take the car doors as another example. The car_front_L_door is constrained to the car_body through TPJoint - Hinge. Make the car door breakable by enabling the Breakable option. All four doors are constrained by their TPJoint helpers; we can decide which doors to fly away due to the explosion by tweaking those joints individually.

To make the explosion directable, we place some geometries inside of the car as sources for particle emitters. For example, the Sphere_core_002 is put under the engine hood. In the tP's dynamic set, it is added  to the MatterWaves operator. Then the Major_Explo_2 particles emit from the Sphere_core_002. Since the direction of particles is based on the surface normal of the Sphere_core_002, we can easily adjust the angle of explosion by transforming the Sphere_core_002 geometry, without any complex mathematical formulation.

Directability is very important in every FX setup. Not only can we decide where the center of an explosion is, we can also control when to trigger the blasts. The screenshot above shows the two explosions controlled by Time Interval condition in tP. In this car explosion animation, the first blast happens at frame 44, then is followed by a smaller blast at frame 100. Through that degree of control over the particles, we can orchestrate the explosion both spatially and temporally.

Variation in the smoke color can enhance visual realism. That's why we generate two sets of dust particles (v_dust_A and v_dust_B), each one used for two Fire/Smoke sources that are set to different RGB colors. Again, this idea is borrowed from the Artillery Explosion tutorial.

The screenshots above show the dynamic sets for particles as Fire/Smoke emitter nodes. First, particles are generated from the surface of any given geometry (car seats for example). Then, when the car explodes, the particles continue to emit from the car seats even when the seats are in mid-air.

It can be very tricky to make both fire and explosion look good in the same scene. You tend to get over-exposure in the fire or under-exposure in the explosion and vice versa. The key is to find an optimal value for the fire and explosion's temperature, in combination with the Color Ramp and Curve in the Volumetric Render Settings of a Fire/Smoke Simulator. In this case, set the Temperature for the fire source to 1800.0 and 4000.0 for the explosion source. I find those values are pretty optimal for both fire and explosion, maintaining all the details in the rendering without clipping too much.

See how temperature from the fluid source plays an important role in the proper exposition of the fire. When the temperature is set to 1800, it shows more details in its hottest parts.

The simulation setup consists of a highly viscous liquid which is emitted from a teapot.

The emission was masked by using a Stucco texture, so the yellow-slimy liquid seemed to come out from small pores on the teapot. I used the same texture to map the viscosity of the Liquid source. To make the animation more interesting, I assigned a Waveform controller to the Outgoing Velocity of the liquid source. A V-Ray Dome light was used for the lighting, the HDRI is from Chaos Cosmos (Studio 002).

Because the liquid runs out so fast, I increased the Steps Per Frame to 2, so we can have a smoother, connected-liquid mesh. I lowered the Gravity to 0.1, so the liquid can emit higher. I also decreased the Time Scale to 0.5 for aesthetic reasons, allowing the viewer to see the effect better.