Ryan and Dennis from the FLIP Fluids development team show you how to quickly improve your workflow with their bestselling Blender add-on. By the way, if you prefer watching to reading, scroll all the way down for a video of Ryan and Dennis talking you through these top tips!
1. Simulation debugging in FLIP Fluids
Did you know that the debug features in FLIP Fluids can be used to diagnose and resolve issues in your simulation setup?
Let's take a common problem as an example: you have modeled a fantastic looking bottle or the most perfect mug Blender has ever seen but when you try to fill it up with your favorite liquid, you find that your fluid just leaks all over the place. What a mess!
So...why is the fluid leaking?
The reason is likely that your model is too thin for your simulation resolution. The FLIP Fluids add-on is a grid-based simulator where physics equations are solved on a 3D grid and the resolution value controls how detailed the grid is. Let's visualize the grid by turning on the Display Grid option in the debug panel.
After enabling the Display Grid option, you will see a visualization of the simulation grid and how the grid is divided into cells. The size of a grid cell can be understood as the smallest amount of detail that will show up in your fluid simulation.
Example: the smallest droplets, the thinnest splashes, and the minimum thickness of an obstacle. The grid display mode is interactive - try adjusting the domain resolution or scaling and resizing the domain to get a better understanding of how the grid changes.
To prevent thin obstacles from leaking, the thinnest parts of the obstacle should be at least one grid cell thick. You can make sure that your obstacle is thick enough by either re-modeling your object walls to be thicker or by increasing simulation resolution.
Another way to check that your obstacle will work well in your simulation is to set the Enable Obstacle Debugging checkbox. This option will output a debug mesh that will show you how the add-on converts the obstacle and how it 'sees' the obstacle within the simulation. After enabling this option, you will need to begin baking the simulation to generate this debug mesh. If your obstacle is not animated, you can stop baking after the first frame is completed and reload the frame to display the debug mesh. If your obstacle object is too thin, you will see holes, cracks, or other errors in the debug mesh where the fluid will leak out. (read the rest of the article on Blender Market blog)