Numerical Simulations of Bouncing Jets

TL;DR

This paper uses numerical simulations to explore the conditions and fluid properties that enable bouncing jets, emphasizing the importance of a thin air layer and adaptive finite element methods.

Contribution

It introduces a numerical approach combining Navier-Stokes projection and level set methods with adaptive finite elements to study bouncing jets.

Findings

A thin air layer is crucial for jet bouncing.

Adaptive finite element refinement captures the air layer effectively.

Rheological properties influence the bouncing phenomenon.

Abstract

Bouncing jets are fascinating phenomenons occurring under certain conditions when a jet impinges on a free surface. This effect is observed when the fluid is Newtonian and the jet falls in a bath undergoing a solid motion. It occurs also for non-Newtonian fluids when the jets falls in a vessel at rest containing the same fluid. We investigate numerically the impact of the experimental setting and the rheological properties of the fluid on the onset of the bouncing phenomenon. Our investigations show that the occurrence of a thin lubricating layer of air separating the jet and the rest of the liquid is a key factor for the bouncing of the jet to happen. The numerical technique that is used consists of a projection method for the Navier-Stokes system coupled with a level set formulation for the representation of the interface. The space approximation is done with adaptive finite elements. Adaptive refinement is shown to be very important to capture the thin layer of air that is responsible for the bouncing.