Rebound of large jets from hydrophobic surfaces in low-gravity

When an oblique water jet impacts a sufficiently hydrophobic substrate the resulting landing flow may give rise to a secondary jet. The parametric range of terrestrial jet rebound research is limited due to the presence of gravity. By employing a drop tower in this investigation we have the opportunity to significantly extend regimes, since in such free fall environments brief relative low-gravity levels <10^-4g₀ are readily achieved. This extended parameter range reveals unique flow structures including fishbone splashing and double-rivulet rebounds. The drop tower test data is used to compile a regime map showing the landing flow structures dependence on the relevant dimensionless groups. We develop simple models predicting landing geometry and the onset of instability that are found to yield good agreement with experiments.