Influence of an upper layer liquid on the phenomena and cavity formation associated with the entry of solid spheres into a stratified two-layer system of immiscible liquids

Benedict C.-W Tan,Peter J Thomas

doi:10.1063/1.5027814

Abstract

New phenomena not previously documented in the available literature have been experimentally observed subsequent to the entry of falling steel spheres into a stratified system of a shallow layer of sunflower oil above a deep pool of water. Further experiments on similar sphere entries into sunflower oil demonstrated that these phenomena arose mainly as a result of the interaction between the surface of the spheres and the sunflower oil. It should be noted that the sunflower oil layer in the aforementioned two-layer system was relatively very thin compared to the dimensions of the spheres. Therefore, the experiments showed the substantial influence both the upper layer liquid and the surface conditions of the solid body could potentially have on the phenomena and cavity dynamics that arise as a result of solid entries into stratified two-layer systems of immiscible liquids.

Highlights

The entry of solid bodies into water and their associated phenomena have long fascinated mankind
The experiments showed the substantial influence both the upper layer liquid and the surface conditions of the solid body could potentially have on the phenomena and cavity dynamics that arise as a result of solid entries into stratified two-layer systems of immiscible liquids
One could interpret from the figure that should all other qualities remain constant, the quasi-static seal, shallow seal, deep seal, and surface seal would be observed in increasing order of impact velocity

Summary

Introduction

The entry of solid bodies into water and their associated phenomena have long fascinated mankind. A solid body possessing appropriate surface conditions and sufficient impact velocity generates a cavity at its wake subsequent to its entry into water or other liquids. The cavity expands while connecting the solid body to the liquid surface prior to a pinch-off arising from the combined influence of hydrostatic pressure, atmospheric pressure, and surface tension forces. This pinch-off splits the cavity into two, and the process is known as the “deep seal” in the literature as it occurs at a significant depth below the liquid surface as compared to other cavity sealing phenomena. The lower cavity remains attached to the solid body and may experience further pinch-offs, splitting into multiple smaller cavities

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