In this tutorial we show how Phoenix works together with tyFlow.

We generate particles using tyFlow. When bombs hit the ground, bounced particles are procedurally created.

tyFlow's particles contain velocity data and Phoenix can use this data as a source for fire and smoke to produce realistic explosion plumes.

The structure of this tutorial is very similar to another tutorial - Artillery Explosion. However, in this article, we put more attention on the pyro shader and add more details to the fire components. The explosion and rising dust are set to different RGB colors. Together with the color gradient in the volumetric shading, we get colorful and rich result in the final shading.

We take advantage of the Time Base - Particle Age, a powerful feature of the Fire/Smoke Source. It allows you to animate the emission of fluid based on the age of each individual particle.

This simulation requires tyFlow v0.16089 (Beta), Phoenix 4.10 Official Release and V-Ray Next Official Release for 3ds Max 2015 at least. 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.

Press the Download button below to get an archive with the start and end scenes.

This download package does not contain the HDRI maps used in the scene. However, you can download the HDRI maps (quarry_02, made by Sergej Majboroda) from the HDRIHeaven website.

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 slower, while mid-to-small scale simulations have lots of vigorous movements.

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.

The Phoenix solver is not affected by how you choose to view the Display Unit Scale - it is just a matter of convenience.

As the focus of this tutorial is a large-scale simulation, setting the units to Meters is a reasonable choice.

Go to Customize → Units Setup and set Display Unit Scale to Metric Meters. Also, set the System Units such that 1 Unit equals 1 Meter.

The final scene consists of the following elements:

1. Plane-bomb-emitter is the plane where the bombs are generated;
2. Five tyFlow nodes: tyFlow-Bombs, tyFlow-major_explo, tyFlow-V_dust, tyFlow-falling_fire and tyFlow-ground_fire;
3. Phoenix Fire/Smoke Simulator;
4. There are total of four Phoenix Fire/Smoke Sources, each representing different component of the explosion;
5. V-Ray Light Dome for lighting;
6. V-Ray Physical Camera for rendering;
7. Shelled Plane001- collision for ground plane;
8. A car object for creating a sense of scale in the scene;
9. Phoenix Plain Force as a wind force in the scene;
10. A point helper for camera shake.

Underneath the ground plane, at the right corner, you can find geometries that produce the explosion procedurally.

1. Bomb as the bomb itself;
2. Cone_V_Dust, Cylinder-ground-fire, Sphere_core001, and Sphere_core002 are the geometries appearing when the bomb hits the ground. They provide the position for the particle emission, allowing us to generate the raised dust and particles for the major explosion.

Camera Setting

Lighting

Here is a preview animation of the particle simulation in its current state.

The bomb particles are generated from the emission plane. Once the bombs hit the collision plane, four different helper geometry instances are created at that spot: Cone_V_Dust, Cylinder-ground-fire, Sphere_core001, and Sphere_core002. This way our setup looks like this:

1. tyFlow-Bombs particles are generated from the surface of Plane-bomb-emitter;

2. Major_explo particles are generated from the surface of Sphere_core001;

3. V_dust particles are generated from the surface of Cone_V_Dust;

4. Ground_fire particles are generated from the surface of Sphere_core002;

5. Falling_fire particles are generated from the surface of Cylinder-ground-fire.

Here is a list of tyFlow particle groups. It summarizes all the different particles and the geometry instances they are using. Every group is color-coded, so you can easily recognize it in the viewport.

Anatomy of the Artillery Explosion

Here are sample renders of the final simulation, so you can have a better idea of the result each particle group produces.

Go to Modify Panel → Create → Geometry → PhoenixFD → FireSmokeSim.

The exact position of the Phoenix Simulator in the scene is XYZ: [ -8.5, 0.25, 0.0 ].

Open the Grid rollout and set the following values:

Select the Phoenix Simulator → Output rollout and enable the output of Temperature, Smoke, RGB, Velocity and Fuel Grid Channel. 

We are going to create four different Fire/Smoke Sources. As an overview, we list them here first. Among those sources, only major_explo emits fuel and explodes, as the name implies.

The other sources are:

• Ground_fire emits the fire on the ground;
• falling_fire creates the fire trail, coming out of the big explosion;
• V_dust is created when the bomb hits the ground and rises up in a V-shape. 

Let's create the sources.

Create a Phoenix Fire/Smoke Source in the scene: Modify Panel → Create → Helpers → PhoenixFD → PHXSource. Rename it to PHXSource_V_dust.

Press the Add button to choose which geometry to emit and select the tyFlow-V_dust entry in the Scene Explorer.

For PHXSource_V_dust:

Set the Emit Mode to Volume Inject and Smoke to 0.2. Disable the Temperature option. Enable the RGB option and set it to light gray color (RGB: 223, 199, 184); Motion Vel. to 1.0; Prt Shape to Sphere, custom; Custom Prt Size to 0.15 m.

From frame 17 to 24, animate the value of Inject Power from 1.5 to 1.0.

Go to Graph Editors/Track View → Curve Editor and check the curve of PHXSource_V_dust's Inject Power.

Set the first key frame to Tangents to Slow and the second key frame to Tangents to Fast.

Set the Phoenix Simulator → Simulation rollout → Start Frame to 16 so that it matches the first frame when tyFlow's bomb hits the ground.

Here is a Preview Animation of the simulation up to this step.

Add a Phoenix Fire/Smoke Source: Modify Panel → Create → Helpers → PhoenixFD → PHXSource. Rename it to PHXSource-major_explo.

Press the Add button to choose which geometry to emit from and select the tyFlow-major_explo entry in the Scene Explorer.

For PHXSource-major_explo:

Set the Emit Mode to Volume Inject, Temperature to 2200 and Smoke to 0.9. Enable the Fuel option, and set it to a value of 1.0. Enable the RGB option and set it to a dark gray color (RGB: 10, 10, 10); Prt Shape to Sphere, custom; Custom Prt Size to 0.15 m.

From frame 17 to 22 animate the value of Inject Power from 1.0 to 0.0.

You can go to Graph Editors/Track View → Curve Editor and check the curve of PHXSource-major_explo's Inject Power.

Set the first key frame to Tangents to Slow and the second key frame to Tangents to Fast as shown.

To allow Phoenix to burn the fuel from Major_Explo source, select the Simulator and go to the Fuel rollout. Check the Enable Burning option and leave all settings as default for now.

Here is a preview animation of the simulation after the last step. Now we see the explosion and the burning fuel, but the smoke looks too thin.

Let's see how to enhance it.

The default render setting of the Smoke color is Constant Color for the entire smoke volume. Let's change it and get more variation.

Select the Phoenix Simulator → Rendering rollout and press the Volumetric Options button.

In the Volumetric Render Settings window set the Smoke Color to be Based on RGB. Set the Smoke Opacity to be based on Smoke and then adjust the curve as in the screenshot.

Here's a preview of the simulation with the render settings changed.

Now we have thicker smoke appearance and the color variation of the smoke looks more convincing. However, V_dust appears too uniform. Let's tackle that.

Let's give the V_dust some randomness.

Set PHXSource_V_dust's Noise to 0.4.

Run the simulation again.

Let's see a preview animation. Notice that V_dust now looks more organic. However, although many bombs hit the ground, we can only see one fiery explosion in the preview. In the next step, we are going to take care of that.

Thanks to the Time Base option in the Fire/Smoke Source, we can do it in a smarter way.

Set the Time Base to Particle Age instead of Absolute. We simply shift-move the keyframes to begin at frame 0. The Fire/Smoke Source reads the particle age information from tyFlow, so we can have sources emitting fluid with animated strength procedurally.

Shift-move all the keyframes of the two Fire/Smoke Sources to the first frame. This table shows the positions of the new keyframes.

Go to the Phoenix Simulator → Simulation rollout and enable the Start Frame Timeline.

With the new position of the keyframes and the Time Base set to Particle Age, run the simulation again.

Now we start to see multiple explosions in the scene. To improve the fluid simulation, let's switch the conservation method to PCG Symmetric in the next step.

Select the Phoenix Simulator and change the Conservation Method to PCG Symmetric, with a Quality of 40. The PCG Symmetric option is the best method to use for smoke or explosions in general, preserving both detail and symmetry. The high Conservation Quality allows the dust to swirl better. For in-depth information, check the Conservation documentation.

With the new Conservation Method, run the simulation again. As you can see, our fluid simulation's movement is more realistic now.

Add a Phoenix Fire/Smoke Source: Modify Panel → Create → Helpers → PhoenixFD → PHXSource. Rename it to PHXSource-ground-fire.

Press the Add button to choose which geometry to emit from and select the tyFlow-ground_fire entry in the Scene Explorer.

Set the Emit Mode to Surface Force and Smoke to 0.2. Enable the RGB option and set it to dark gray color (RGB: 49, 49, 49); Motion Vel. to 1.0; Time Base to Particle Age. Prt Shape to Sphere, custom; Custom Prt Size to 0.3 m.

From frame 0 to 70 animate the value of Outgoing Velocity.

Also, from frame 0 to 90, animate the value of Temperature from 1600 to 1545. Details of the animation curve are shown in the next step.

Go to Graph Editors/Track View → Curve Editor and set keys to the curve of PHXSource-major_explo's Outgoing Velocity and Temperature. We set keyframes to Outgoing Velocity and Temperature, so both change over time. Each frame and value are shown in the screenshots. All keyframes are set to Tangents to Linear.

Run the simulation again.

Here is a preview animation of the simulation after the last step. Although we have added the ground_fire source to the sim, we still can't see any ground fire in the preview and this is the next thing we will take care of.

Let's give V_dust some randomness.
Set PHXSource_V_dust's Noise to 3.0.

Run the simulation again.

Let's see a preview animation of this simulation run. Now we start to see ground fire in the preview. The fire grows gradually once the bombs hit the ground.

Create a Phoenix Fire/Smoke Source in the scene: Modify Panel → Create → Helpers → PhoenixFD → PHXSource. Rename it to PHXSource_falling_fire.

Press the Add button to choose which geometry to emit from, and select the tyFlow-falling_fire entry in the Scene Explorer.

For PHXSource_falling_fire:

Set the Emit Mode to Surface Force and Smoke to 0.03. Set the Temperature to 1800. Enable the RGB option and set it to dark gray color (RGB: 49, 49, 49); Motion Vel. to 1.0; Time Base to Particle Age. Prt Shape to Sphere, custom; Custom Prt Size to 0.4 m.

From frame 0 to 90 animate the value of Surface Force. Details of the animation curve are explained in the next step.

Go to Graph Editors/Track View → Curve Editor and set keys to the curve of PHXSource_falling_fire's Outgoing Velocity. We set keyframes to Outgoing velocity, so it can change over time. Each frame and value are shown in the screenshots. All keyframes are set to Tangents to Linear.

Run the simulation again.

Here is a Preview Animation of the simulation up to this step.

As the viewport preview is just an approximation of the final rendering, let's run test renders for frame 50 and frame 90.

We want our explosion to be more fiery and volatile. So, increase the Smoke Threshold in the Simulator's Fuel rollout to 0.1.

Run the simulation again.

Here is a Preview Animation of the simulation up to this step.

Test render for frame 50 and frame 90. Now the results became brighter with thinner smoke.

We want the bomb to be even more explosive. Let's increase Propagation to 14.0, so the fluid expands faster when the fuel burns.

Run the simulation again.

Here is a Preview Animation of the simulation up to this step.

Test render for frame 50 and frame 90. You can see the explosion expands faster.

The default black body volumetric shading looks a bit dull, so let's make it more interesting in the following steps.

Go to the Fire/Smoke Simulator → Rendering rollout, click on Volumetric Options. Adjust the color gradient and the curve as shown in the image.

Alternatively, load a Rendering Preset from the Smoke_Opacity_curve_and_Fire_color_gradient.tpr file, provided with the sample scene.

Test render for frame 50 and frame 90. With the new color gradient and curve, the fire and smoke become more vivid and violent in terms of color and shading. However, we need more details in the explosion.

To alleviate the washout problem in the shading, let's reduce the Light Power on Self and Light Power on Scene to 0.2.

Render out frame 50 and 90 again. Now we see more details in the explosion.

However, we would also like to see more details in the white smoke in the beginning (frame 50).

Lower the External Scatter Multiplier to 0.2.

Render out frame 50 and 90 again. As you can see, more details in the white smoke appear.

For additional realism to the simulation, we use a Phoenix Plain Force to simulate the effect of wind.

Go to the Helpers tab → Phoenix and add a Phoenix Plain Force. The Plain Force is a simple directional force.

Rotate it so that it points in the positive X direction and set the Strength to 1.5 m. Set the Drag to 0.01. Enable the Apply Force Behind Icon option.

The exact Position of the Plain Force in the scene is XYZ: [ -30, 0, 14 ].

With the Plain Force in the scene, simulate again.

Now the explosion shifts slightly to the right as the wind blows.

Since the whole explosion covers a large region, we have to expand the Simulator grid. In order to get a more detailed result we also increase the grid resolution by lowering the Cell Size for the final simulation.

Move the Phoenix Simulator to XYZ: [ 0.365, 0.25, 0.0 ].

Open the Grid rollout and set the following values:

Here is a Preview Animation of the final simulation.

The final image is rendered using the V-Ray Frame Buffer with the Color Corrections set to:

Exposure:

• Exposure: 2.69;
• Highlight Burn: 0.69;
• Contrast: 0.25.

White Balance:

• Temperature: 7362.

Bloom/Glare Effect is enabled from the Lens Effects panel:

• Size: 16.98;
• Bloom: 0.29;
• Intensity: 1.51.

And here is the final rendered result.