The linear Rayleigh-Taylor instability with foams

TL;DR

This paper analyzes the linear phase of Rayleigh-Taylor instability in foams, revealing stabilization effects in the elastic phase and providing analytical growth rate calculations based on foam micro-structure.

Contribution

It introduces an analytical approach to compute RTI growth rates in foam, highlighting stabilization in the elastic phase and emphasizing the importance of foam micro-structure.

Findings

RTI can be stabilized at certain wavelengths in the elastic phase.

Homogeneous foam models overestimate growth by ignoring elasticity.

Results are potentially applicable across various scientific fields.

Abstract

We analyse the behaviour of the linear phase of the Rayleigh-Taylor instability (RTI) in the presence of a foam. Such a problem may be relevant, for example, to some inertial confinement fusion (ICF) scenarios such as foams within the capsule or lining the inner hohlraum wall. The foam displays 3 different phases: by order of increasing stress, it is first elastic, then plastic, and then fractures. Only the elastic and plastic phases can be subject to a linear analysis of the instability. The growth rate is analytically computed in these 2 phases, in terms of the micro-structure of the foam. In the first, elastic, phase, the RTI can be stabilized for some wavelengths. In this elastic phase, a homogenous foam model overestimates the growth because it ignores the elastic nature of the foam. Although this result is derived for a simplified foam model, it is likely valid for most of them. Besides the ICF context considered here, our results could be relevant for many fields of science.