With the release of Houdini 21 I decided to look into the new Machine Learning nodes by creating this liquid simulation model. I went through many struggles with understanding this project and finding resources, so to help other Houdini artists looking to understand the base pipeline for creating a regression model I have made a how to blog post on this subject: https://www.artstation.com/blogs/zoeedwards/n7e69/how-to-ml-in-houdini
Liquid Simulation from regression model