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The instructions on this page guide you through the process of setting up an effervescent tablet simulation.

This simulation requires Phoenix 4.41 Nightly Build from 27 August 2021 and V-Ray 5, Update 1.1 for Maya 2018 at least. You can download nightlies from https://nightlies.chaos.com or get the latest 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 Download button below provides you with an archive containing the scene files.

To download project files:

Want to follow along but don’t have a license?:

With the generated curve selected, go to Surfaces → Revolve. 

As Phoenix can't use the generated NURBS surface directly, we need to convert it to polygons.
Select the generated surface and go to Modify → Convert → NURBS to Polygons (options).
Set the Tessellation method to Control points.

The resulting geometry is likely to be very low-res so consider subdividing it before using it for simulation.
Go to Mesh → Smooth (options) and set the Division Levels to 2.

It would be a good idea to save the curve and the NURBS surface that you created earlier in a group node which you can then hide.
Rename the glass to glass_geo_01.

To generate the Initial Fill geometry, select the inner faces of the glass.

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Use the Mesh → Fill Hole command to fill the top of the generated geometry. Phoenix can't use an open mesh as a source.

Be sure to reverse the normals of the geometry as it is very likely that they will be pointing inwards. To do so, go to Mesh Display → Reverse.

You could use a 3rd party plugin to create a comprehensive RBD simulation of a tablet dissolving into smaller and smaller pieces as they travel upwards and use that.

We use a simple polygon cylinder to represent the tablet.

Rename the tablet geometry to source_geo_01.

The tablet has an animated Solid option, so the geometry is a Solid object till frame 24 and then it becomes a Non-Solid object.

Select the tablet geometry and go to Attributes → Phoenix FD → Phoenix FD Node Properties → Extra Phoenix FD Attributes. As you can see the Solid option is enabled by default.

Go to frame 24, leave the Solid option enabled and Set Key. Then, go to frame 25, disable the Solid option and Set Key.

Set the Emit Mode to Surface Force and disable Emit Liquid. We are not looking to add more fluid into the simulation. The Source is used to generate bubbles only.

Lets animate the Discharge value:

Frame 14: 0;
Frame 40: 1;
Frame 100: 1.5;
Frame 200: 1;
Frame 250: 0.5. 

Set the Noise to 1.

This option varies the Discharge across the surface or the volume of the emitting geometry or particle. The variation also changes over time. This is a shorthand for using an animated Noise texture in the Mask slot.

Enable Particles and set the Particles Type to Foam.
The amount of born Foam particles is animated in time so that the Foam is emitted only when the tablet geometry is underwater:

Frame 15: 0;
Frame 17: 9;
Frame 18: 12;
Frame 61: 10;
Frame 200: 6;
Frame 250: 0. 

When the Motion Velocity checkbox is enabled, the moving tablet geometry will affect the velocity of the foam particles and make them follow the emitter. As we want this effect to be less pronounced we will lower its value.

Enable Motion Velocity and set its value to 0.2.

Go to the Liquid tab and select Enabled.

Navigate to the Grid rollout and set the Scene Scale to 4. When working with small scale water simulations, it's often hard to control the tiny jittering that tends to occur near collision objects without increasing the Steps Per Frame to prohibitively high values. Therefore, it's faster and easier to simply increase the Scene Scale a little.

Set the Cell Size to 0.2. Working with a low Grid Resolution allows for much faster iteration and playback.

Set the Container Walls to Jammed Both for X and Z, and Jammed(-) for Y. When the walls are set to Jammed Both, the simulation behaves as if there is a solid boundary in both directions and the liquid collides with the side walls of the Simulator. Setting the walls to Jammed(-), means that the simulation behaves as if there is a solid boundary in the negative direction. In our case, the liquid is colliding with the bottom and side walls of the Simulator and the liquid is not flowing right through the glass walls. 

The scene uses a very low Grid Resolution - only 600K voxels, because the liquid does not need much detail and the main focus is on the Foam particles.

Go to the Scene Interaction → Exclude List. This option determines which objects will be ignored or processed by the simulation. If you have a large (complex) scene and you wish only certain objects to participate in the simulation, you can disable the Exclude List and add the objects in the Simulation Set.

In the Scene Interaction tab, uncheck Exclude List and Exclude Hidden Objects. This gives us full control over what goes into the Phoenix simulation and thus, if any issues arise, makes troubleshooting much easier.

Now that Exclude List is unchecked, the phx_sim_set works as an include list - in other words, we need to add any geometry or source that will be used in the simulation to that set.

Add source_geo_01, phx_source_01, glass_initial_fill_01 and glass_geo_01 to the phx_sim_set.

Set the Foam Amount to 0. The Foam generation will be handled by the Liquid Source, not the Simulator. This parameter is responsible for generating foam from turbulent liquids and we're not interested in doing that.

Set Half Life to 0. This parameter controls the total lifespan of the Foam. However, because our foam is generated inside the liquid, it won't die until it reaches the surface - which is exactly the desired behavior.

Set the Size to 0.09. Foam Variation Small is set to 8, while Variation Large is set to 0.7, so that the smallest bubbles would be much smaller than the Foam Size, while bigger bubbles would not be much larger or they would appear unnatural.

The Size Distribution is set as high as 400, so that there will be a very large number of small bubbles, but not many larger ones.

Set the B2B Interaction to 100. The Bubble-To-Bubble interaction helps the Foam particles stick together rather than behaving like individual points in space.

Set the Rising Speed to 8. This option affects only the foam particles which are inside the liquid volume. This is the maximal speed of ascent of the average-sized bubbles. Bubbles larger than the Size parameter rise faster and smaller bubbles rise more slowly. If the Rising Speed is too high, foam particles will shoot past the liquid surface into the air.

Set the Surface Lock to 1. This allows you to control the behavior of the foam inside the liquid. If the Surface Lock is set to 1, the foam will be forced to float exactly at the liquid surface, regardless of any motion that may otherwise temporarily force it to sink into the water. Setting it to 0 disables this behavior and the values in-between act as a multiplier for the effect.

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Enable the Volume Light Cache.

Set the Light Cache Speedup to 0.990.

In this example scene, the Volume Light Cache is used for speeding up the rendering process. 

You may experiment with the Light Cache Speedup value to see which value works best with your setup.

Check the Particle Shader page for more information about the Volume Light Cache option.

Go to the Bubbles | Cellular | Splashes tab:

- set Refraction Index to 1.2;
- set Bounces to 6;
- set Reflection Cut Off to 0.01;
- set Highlights Width to 0.5;
- set Highlights Strength to 1;
- set Pressure Variation to 5.

All of those can and should be modified to fit your needs. Lower Highlights Width values will produce glossy bubbles. The Highlights Strength controls the brightness of the reflection.

For the water material applied over the Simulator, set the Diffuse Color to RGB (0, 0, 0).

Set the Reflection and Refraction Color to RGB (255, 255, 255), and the Refraction IOR to 1.33.

Enable Affect Shadows - without this option, the bubbles will appear black in the rendered image.

Navigate to the Reflection - advanced rollout and set the Max depth to 5.

You can leave the Max depth parameter at its default value of 8 or switch it to a higher value. The Reflection Max depth specifies the number of times a ray can be reflected.

In this example scene, the Reflection Max depth is set to 5, as this value works good for the scene setup and we save on some render time.

Scroll to the Refraction - advanced rollout and set the Max depth to 10.

You can leave the Max depth parameter at its default setting of 8 or switch it to a higher value. The Refraction Max depth specifies the number of times a ray can be refracted.

For this setup a standard Camera and Aim are used.

The Angle of View is set to 39.6.

The Focal Length is set to 50.

The exact position of the Camera is [ 0, 16, 62 ] and of the Camera Aim is [ 0, 7, -5 ].

Set the V-Ray Sampler type to Bucket.

Set the Min subdivs to 1 and the Max subdivs to 6.

Set the Threshold to 0.001.

Set the Render region division to 16.

The Ramp texture in this example scene is set as follows:

Type: Circular Ramp;

Interpolation: Exponential Up;

The first point has the U Wave set to 0, and the Selected Color is set to RGB (135, 202, 255).

The second point has the U Wave set to 0.8, and the Selected Color is set to RGB (21, 94, 255).

For the final render, some corrections are made in the V-Ray Frame Buffer.

Create Hue/Saturation Layer and set the Saturation to 0.1.

Create Curves Layer and set the points to the following positions:

• first point to (0.004, 0.017);
• second point to (0.984, 1).

Feel free to use other values for the post effects depending on your preferences.