The resolution of a fluid is defined in voxels (volume pixels). Higher resolutions produce finer detail, but increase rendering time. (Performance can be affected if the total number of voxels is significantly over 3 million, which is equivalent to a 150×150×150 3D fluid.) Changing the fluid resolution affects the properties currently defined in the container.
Fluid resolution is set along the X and Y axis of 2D containers and along the X, Y, and Z axis of 3D containers. You can adjust the resolution values proportionally along each axis, which results in square voxels in the container. Adjusting fluid resolution non-proportionately without adjusting the size to match, for example setting the resolution along the Y axis to a higher value than the X and Z resolution values, results in non-square voxels in the container.
To maintain square voxels in your fluid regardless of the fluid resolution, ensure that the Keep Voxels Square attribute is on. With Keep Voxels Square on, voxels in the container are kept square by keeping the X,Y, and Z Resolution values proportional to their respective Size values.
For example, if the X,Y, and Z Size values of a 3D container are 10, and the X, Y, and Z, Resolution values are 10, increasing the container's size along the Y axis to 20 results in the X and Z Resolution values being scaled down from 10 to 5. This ensures that the container’s voxels are kept cubic.
When you create new fluid containers, Keep Voxels Square is on. If you open a scene file from a previous version of Maya, Keep Voxels Square is off.
With Keep Voxels Square on, fluid resolution can be adjusted using the Base Resolution attribute. Base Resolution adjusts resolution for all of the container’s axis at the same time. The highest resolution value among the containers axis is set as the Base Resolution value. The resolution values of the other axis are appropriately scaled down, if necessary, to maintain square voxels.
Some fluid example files provide better results when Keep Voxels Square is off.