# Swirling against the forcing: evidence of stable counter-directed sloshing waves in orbital-shaken reservoirs

## TL;DR

This paper investigates the surface wave behavior in a cylindrical container shaken elliptically, revealing stable counter-directed swirling waves and validating findings with an inviscid asymptotic model.

## Contribution

It provides experimental evidence and a theoretical model for stable counter-directed swirling waves in orbital-shaken reservoirs, highlighting the influence of orbit aspect ratio.

## Key findings

- Existence of stable counter-directed swirling waves
- Experimental validation of wave behavior
- Model predictions align with observed phenomena

## Abstract

We study the free surface response in a cylindrical container undergoing an elliptic periodic orbit. For small forcing amplitudes and deep liquid layers, we quantify the effect of orbit's aspect ratio onto the surface dynamics in the vicinity of the fluid system's lowest natural frequency. We provide experimental evidences of the existence of a frequency range where stable swirling can be either co- or counter-directed with respect to the container's direction of motion. Our findings are successfully predicted by an inviscid asymptotic model, amended with a heuristic damping.