Making a Splash: A Numerical Study of a Hydrophobic Solid Sphere Entering Water

We’ve all seen what happens when we drop a stone into a pond – it makes a splash, dives under the surface, and eventually sinks to the bottom. But what if the stone didn’t want to get wet? What if it was hydrophobic, meaning it tends to repel water?

In this project, I’m using advanced computer simulations to study exactly that: what happens when a hydrophobic (water-repelling) solid sphere enters a free water surface. This isn’t your everyday splash in the pond. It’s a complex dance of physics and fluid dynamics that’s both fascinating to study and important for a range of industries.

To perform this study, I used tools called CLSVOF (Coupled Level Set and Volume of Fluid) and a Navier-Stokes solver. These are like high-tech virtual laboratories that let us study the behavior of liquids and solids in great detail, right down to how the sphere moves and how it interacts with the water because of its hydrophobic nature

This simulation revealed some intriguing phenomena that depend on how fast the sphere enters the water:

  1. Surface Seal: When the sphere isn’t moving too fast, it sort of “seals” the water surface as it enters, with the water closing over it.
  2. Shallow Seal: At somewhat higher speeds, the sphere makes a “shallow” seal as it enters the water, creating a different interaction with the surface.
  3. Deep Seal: At high speeds, the sphere pushes deep into the water before the surface closes over it, forming a “deep” seal.

These findings help us understand not just the splash you see when an object enters water, but the complex science behind that splash. The insights could be used in industries from maritime engineering to aquatic sports design.

 

This project is currently in the process of publication, so watch this space for more exciting updates!