# Shock wave induced cavitation of silicone oils

## TL;DR

This study investigates how shock waves induce cavitation in silicone oils using flyer plate impact experiments, revealing that cavitation occurs via homogeneous bubble nucleation regardless of viscosity or strain rate.

## Contribution

It provides experimental data on cavitation thresholds in silicone oils under shock loading and compares results with models, highlighting bubble nucleation as the primary cavitation mechanism.

## Key findings

- Cavitation threshold remains constant across viscosities and strain rates.
- Homogeneous bubble nucleation dominates cavitation onset.
- Experimental results align with nucleation-based cavitation models.

## Abstract

The cavitation threshold of polydimethylsiloxane (silicone) oils was studied using the planar impact of flyer plates to generate large transient negative pressures within the liquids. The plate-impact experiments used a 64-mm-bore gas-gun to launch thin sabot-supported flyer plates onto liquid capsule targets in which a thin Mylar diaphragm formed a free surface at the back of the sample. The shock wave driven into the target capsule by the flyer impact placed the silicone oil in tension upon reflection from the rear free surface, eventually causing the sample to cavitate. The spall strength, or critical tension which cavitates the liquid, was determined by monitoring the free-surface velocity using a photonic Doppler velocimetry system. This study explored the effect of viscosity and loading strain rate on a system of three silicone oils having vastly different viscosities (4.8$\times$10$^{-2}$ Pa s to 2.9$~\times$10$^{1}$ Pa s), but otherwise similar properties. The spall strength was found to remain constant over the ranges of strain rate and viscosities probed in this work. A comparison of the experimental results to models for the cavitation threshold of liquids suggested that homogeneous nucleation of bubbles was the dominant mechanism for tension relief at the onset of cavitation.