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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 the setup is identical to the Burning Chair tutorial for 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.

Add the riverRoots geometry to phxsim_set1 by Middle-Mouse-Button drag&dropping it in the Outliner.

The automatically generated simulation set can be used to specify which objects in the scene will interact with the Phoenix Simulation.

By default, the set acts as an Exclude List ( Simulator → Scene Interaction rollout), meaning that objects inside the set will be ignored during the simulation.

Select the riverBed geometry and go into Face Selection mode (F11). Select the faces at the very start of the stream and assign a new Lambert material to them.

Rename the new material to mat_emit_liquid and give it a fabulous Diffuse Color.

Select the Phoenix Liquid Source and set the Emit Material parameter to point to mat_emit_liquid. You can do this either by:

1. Manually typing the name in the Emit Material field and hitting enter.
2. Middle-Mouse-Button drag&dropping the material from the Hypershade window.

The Source will now only emit from faces that share this material.

Here's a preview of the simulation in its current state.

One major issue at the moment is the fact that it takes about 250 frames for the river bed to fill up with water. This can become a major issue when running high-res simulations and tweaking individual parameters for the Foam, Splashes, etc.

There are two ways to address this:

1. Run the simulation for 200 or so frames and use the Simulation rollout → Load & Start button to start a new simulation from the last frame of the one before.
2. Enable Dynamics → Initial Fill Up to fill the Liquid Simulator with water on the first frame of the simulation.

We go with the second approach.

To enable the simulation of WetMap Particles, enable Wetting from the Simulator → Liquid rollout.

Wetting is a simulation, not a render-time option - changing any of the values below requires a re-run of the simulation.

Run the simulation for 30 or so frames.

Right Mouse Button click on an empty space in the Outliner and Disable the Show DAG Objects Only option. The Phoenix Particle Groups generated by the Simulator are not visible by default - disabling this option will allow you to select them.

When created, the Phoenix Particle Texture generates a set used to specify which particle groups will be evaluated. You need to provide the WetMap Particle Group to the set so the Particle Texture can use it.

Middle Mouse Button click&drag the PG_PhoenixFDSimulator1_WetMap_0 into the set phxParticleTex_set1.

A 3d Placement Node is also generated automatically. Do not delete it - Phoenix needs this node to properly map the texture to your geometry.

Increase the Particle Area Radius (units) parameter until the dots generated by each WetMap particle start blending together.

For this example, the value is set to 5.

Here's a preview of the Splash particles on their own:

In the next step, we enable the simulation of Foam.

Reduce the Grid → Cell Size to ~2cm for the final simulation and hit Simulation → Start. Consider disabling the Mesh Preview and Particle Preview - reading the cache files and showing their contents in the Viewport becomes progressively slower the heavier a simulation becomes.

To the side is a preview of the final simulation.

We focus on the water material for the liquid, the Phoenix Particle Shader settings and an example V-Ray Blend Material setup using a Wetmap for the river stones.

Let's start by adding a V-Ray Sun&Sky system and a Camera so the lighting setup is taken care of from the get-go.

Add a new camera by going to Create → Cameras → Camera and Aim.

Here are the exact transformations:

Target Translate X/Y/Z: [ -14.3, 566.646, -98.18 ]
Camera Translate X/Y/Z: [ 434.102, 2463.551, -1014.203 ]

Camera Attributes → Focal length is set to 43.2.

Here's a rendered image of the River Bed, River Stones and River Roots geometry.

The Phoenix Simulator and the two Particle Shaders for the Foam and Splashes are hidden to speed up the look-dev process.

Assign a V-Ray Material to the riverStones geometry and plug a Phoenix Particle Texture in the Diffuse slot.

Add the PG_PhoenixFDSimulator1_WetMap_0 node to the automatically generated phx_particelTex_set (recall that Show DAG Objects Only has to be disabled for the Phoenix Particle Group nodes to show up in the Outliner).

Set the Particle Area Radius to 5cm to avoid noise artifacts in the generated black&white texture.

Hit render - only the stones which interact with the liquid should now render white.

Create a V-Ray Blend Material and assign it to the riverStones geometry.

Plug the Phoenix Particle Texture you just created into the Blend1 slot and unplug it from the V-Ray Material's Diffuse slot.

Rename the V-Ray material to mat_dry or something along those lines and pipe it into the Base slot of the Blend material.

Add a second V-Ray material, rename it to mat_wet and plug it into the Coat1 slot of the Blend material.

Here's how this works:

1. The Phoenix Particle Texture generates a black&white map (i.e. a mask).
2. The Blend parameter of the VRay Blend material expects a mask used to specify whether to use the Base material, or any of the Coat materials, or a blend between them).
3. When you plug the Phoenix Particle Texture in the Coat slot, the Blend material will use the Base material for the black areas of the texture and the Coat material for the white areas.
4. As can be seen from the image above, those correspond to the dry and the wet areas of the scene. All that is left to do is tweak the materials to get the desired appearance. For this example, the Reflect color of mat_wet is set to RGB [ 255, 255, 255 ] with a Glossiness of 0.65 so the wet stones are shiny.

Here's a rendered image of all the materials from the example scene that ships with the tutorial files.

The exact same setup is used to drive the V-Ray Blend material using a Phoenix Particle Texture reading the WetMap particle group of the Simulator.

The textures used to generate this image are also provided.

Unhide the Phoenix Simulator and assign a new V-Ray material to it. Rename the material to mat_water.

Set the Reflect and Refract colors to RGB [ 255, 255, 255 ] and the IOR (Index of Refraction) to 1.33. This is the physically-accurate IOR of water - you can use a search engine to look up the IOR of other materials in case your setup is different.

Set the Fog color to RGB [ 246, 251, 251 ] with a Fog multiplier of 0.2. We use the Fog color to tint the water. In the real world, water is tinted because of the microscopic particulates it carries which refract the incoming light. Using the Fog options is an efficient way to emulate this without significantly increasing the render time.

Final image of all scene elements combined.