Solver

Frame Sub-Steps Limit	If your simulation has high velocities and you're seeing noise artefacts in the flow, allow the simulation to take more sub-frame time slices if necessary by increasing this value. This will allow the simulation to resolve the fluid motion better. The simulation will also take more time, though.
Pressure Iteration Limit	Wherever velocity deforms the fluid, pressure is build up. It is a fundamental part of the simulation to equalize this pressure. For simulations that have high velocities and/or collision objects or closed container boundaries, it is recommended to use values between 2 and 10. Values larger than 10 should rarely be necessary. For simulations that don't have collisions and mostly moderate velocities, the simulation time can be kept lower by using the minimum of one iteration.
Adaptive Container	If enabled, TFD simulates the smallest possible part of the container in order to save time and memory. The Clip Below parameters in the Velocity, Temperature, Density, Fuel and Burn tabs control when TFD may shrink the container. Unchecking this box is only useful for benchmarking and testing purposes.

Frame Sub-Steps Limit

If your simulation has high velocities and you're seeing noise artefacts in the flow, allow the simulation to take more sub-frame time slices if necessary by increasing this value. This will allow the simulation to resolve the fluid motion better. The simulation will also take more time, though.

Pressure Iteration Limit

Wherever velocity deforms the fluid, pressure is build up. It is a fundamental part of the simulation to equalize this pressure.

For simulations that have high velocities and/or collision objects or closed container boundaries, it is recommended to use values between 2 and 10. Values larger than 10 should rarely be necessary. For simulations that don't have collisions and mostly moderate velocities, the simulation time can be kept lower by using the minimum of one iteration.

Adaptive Container

If enabled, TFD simulates the smallest possible part of the container in order to save time and memory. The Clip Below parameters in the Velocity, Temperature, Density, Fuel and Burn tabs control when TFD may shrink the container.

Unchecking this box is only useful for benchmarking and testing purposes.

Advection

Velocity/Channel Advection

The advection accuracy affects the sharpness of the details in the fluid.

1st order	produces a somewhat blurrier result where vortices get smoothed away quicker, but it's also faster and uses less memory.
2nd order	produces sharper details, keeps vortices alive longer but uses more time and memory.

Adaptive Tracer

When advecting the fluid, the simulation traces a trajectory through the velocity field for each voxel. The fluid moves along these trajectories.

The default tracer approximates the trajectories with a single line segment. The Adaptive Tracer uses many line segments, such that none of them are longer than the voxel size.

Cubic Interpolation

Moving the channels along the flow requires repeated interpolation. This interpolation slightly blurs the channel each time. Using cubic interpolation reduces this blur at the cost of somewhat higher simulation times.

Misc

Use less memory but more time	Since fluid simulation can be very memory intensive, you are likely to exhaust your system's memory with large simulations. In order to allow you to run larger simulations on machines with less memory, checking this option will let TurbulenceFD use less internal caches which results in less memory being used but more simulation time being required. Render times are not affected.
Collision Objects Enlarge Container	The adaptive container will be enlarged to contain all collision objects by default. This may not be necessary, especially if the objects aren't moving. In such a setup, you can uncheck this option to keep the container smaller.
Smooth Collision Surface Rendering	When rendering solid obstacles emerged in the fluid, extrapolation will avoid artefacts on the surface of the obstacle. If you have invisible or transparent obstacles, disable this option.

Closed container boundaries	By default the sides of the fluid container are open. The fluid can just move out of the container and disappear. If you want to simulate a closed or partially closed space, you can select the sides of the container that will be closed. The checkboxes are labeled according to the half-spaces of the coordinate system. That is, +X is the side of the container in the positive X direction and so on. For example, a ground explosion can be simulated in a container with the -Y side closed to avoid having fluid leave the container through the ground.

Closed container boundaries

By default the sides of the fluid container are open. The fluid can just move out of the container and disappear. If you want to simulate a closed or partially closed space, you can select the sides of the container that will be closed. The checkboxes are labeled according to the half-spaces of the coordinate system. That is, +X is the side of the container in the positive X direction and so on.

For example, a ground explosion can be simulated in a container with the -Y side closed to avoid having fluid leave the container through the ground.