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V-Ray Additional Attributes can be added to any Bifrost simulation from the Attributes > VRay menu in the Attribute Editor. These additional attributes assist in exporting.

UI Path: ||Select Bifrost system|| > Attribute Editor >  Attributes menu > VRay > (select attribute set)

Export voxels – Turns on/off the voxel export from this bifrost shape. Turn on this option when rendering a standard iso-surface or smoke.

Export particles – Turns on/off the particle export from this bifrost shape. Turn on this option when rendering particles or metaballs.

Export density – Turns on/off density export from this bifrost shape.

Interpolation – Choose between Linear or Qudratic interpolation.  Linear is faster to render, but Qudratic produces better quality rendering.

Volume Shader – Determines which volume shader to use.

Auto – Picks the best available shader. In V-Ray 3.0 this always resolves to Phoenix FD. In V-Ray 2.x, Phoenix FD will be used only if available.
VRayEnvironmentFog – Uses a generic purpose volumetric shader that V-Ray is using in VRayEnvironmentFog node.
Phoenix FD – Uses the Phoenix FD shader, which is optimized for grid based volumetric data.

Scatter GI – Enables the tracing of GI through the fluid. The standard GI engine in the V-Ray settings is used.

Scatter bounces – When Scatter GI is enabled, this parameter limits the number of GI bounces that are calculated inside the fog. This can be used to increase rendering performance.

Simplify textures for GI – When this option is enabled,V-Ray uses a simplified method for calculating the GI when rendering parts of the liquid that are textured or are being faded out.

Step size – Determines the size of one step through the volume of the liquid. Smaller steps produce more accurate results but are slower to render. In general, dense volumes require smaller step sizes than more transparent volumes.

Max steps – (VRayEnvironmentFog only) Specifies the maximum number of steps through the liquid. It's purpose is to prevent too many steps inside the volume. However, it can cause parts of the fluid to not render!

Texture samples – (VRayEnvironmentFog only) Determines the number of texture samples for each step through the liquid. This allows the sampling of textures more accurately than the volumetric lighting. It is useful in cases where the textures vary much faster than the lighting itself (e.g. for detailed fractal textures). Note that this parameter is used only with shader.

Cut-off threshold – This parameter controls when the raymarcher stops traversing the volume. If the accumulated volume transparency falls below this threshold, the volume is considered opaque and tracing is aborted. Higher values make the rendering faster, but may introduce artifacts.

Subdivs  – (VRayEnvironmentFog only) Determines the number of points inside the fog at which volumetric lighting is evaluated. If this value is 1, a single sample along the ray is calculated, otherwise the Step size is used instead.

Diffuse color multiplier – Specifies an extra multiplier for the diffuse lighting. This can be used to produce a non-physically correct result. The VRayEnvironmentFog shader requires this parameter to be set to 4.0 in order to produce results similar to the Maya Software renderer. The Phoenix FD shader does this automatically.

Jitter  – Used to offset the starting point of shading in order to hide regular patterns.

Solid mode  – When enabled, the fluid is rendered as a solid object with sharp surface, determined by the Solid threshold attribute.

Solid threshold – Specifies the value bellow which the fluid is assumed to be "solid."

Volume Light Cache – (Phoenix FD only) Enables usage of light cache. This can increase the performance, but can present lighting splotches, especially when used with low resolution grid and noise textures.

Full Motion Blur – Turns on the motion blur caused by the fluid movement inside the container. This is slower then calculating only the motion blur of the fluid container.

Disabled – Disable to increase rendering performance.
Blend – Uses simple fade out between two states of the fluid. Note that this actually doesn't produce fluid moving effect.
Velocity – Uses the velocity field to move the fluid in time. Since this method is using a snapshot of the velocity at the start of the motion blur interval, the end position often doesn't correspond to the start of the next motion blur interval.
Velocity + Blend – Uses the velocity to try blending more accurately between the current and the next frame. This is the most advanced, but slowest method.

Render as Geometry – Enables the bifrost to be rendered as a collection of semi-transparent geometric layers. It allows to output render elements (without it you will see only Alpha and RGB), as well as to generate deep image data when saving to Deep EXR or VRST.

Legacy Phoenix FD Shading – When enabled, bifrost renders with old behavior from previous versions of V-Ray.