There are two type of render-time sub-grid detail. Both work at render time without requiring a re-simulation.
Velocity displacement deforms the fluid during rendering and can produce very sharp details.
Sub-Grid Noise adds detail to the fluid that
Velocity Displacement works only if a Velocity Cache is available (see 
Container). Sub-Grid noise works without a Velocity Cache, but for smooth animation you should also have the Velocity Cache available.
Both options increase the render time.
| Velocity Displacement | Velocity Displacement warps the field forward or backward in time, depending on the value you set. Rendering times will be higher, so this is disabled in fast preview mode. Low values can add more detail while introducing very little noticeable deformation. Higher values can change the appearance of the field very much, but produce interesting effects. Note that you will have to enable Cache Velocity in the Simulation/Cache tab in order to be able to use Velocity Displacement.
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| Noise Intensity | Specifies how strong the noise will affect the shaded fluid. |
| Smallest Size | Specifies the size of the smallest noise. |
| Largest Size | Specifies the size of the largest noise. Note that the larger the difference between Smallest and Largest scale, the more render time will ne needed. |
| Small Power | Specifies how strong small detail is with respect to the next larger ones. A small power of 1.0 will make curls of all sizes equally strong. A small power of 0.5 will make small curls half as strong as curls of twice the size. |
| Period | The turbulence field changes over time. This value specifies the number of frames between it's phases. |
