A buoyancy-drag model with a time-varying drag coefficient for evaluating bubble front penetration depth

TL;DR

This paper introduces an improved buoyancy-drag model with a time-varying drag coefficient to accurately evaluate bubble front penetration depth caused by Rayleigh-Taylor instability, considering multiple physical mechanisms.

Contribution

The paper develops a novel buoyancy-drag model with a dynamic drag coefficient that accounts for various physical effects during bubble growth phases.

Findings

Model shows improved accuracy over classical models.

Control of bubble penetration depth by suppressing dangerous modes.

Validation through simulations under diverse conditions.

Abstract

To evaluate and control bubble front penetration depth ${{h}_{B}}$ induced by ablative Rayleigh-Taylor instability (ARTI) from a weakly nonlinear phase to a self-similar phase, we first propose an improved buoyancy-drag (BD) model with a time-varying drag coefficient. The coefficient incorporates the influence of multiple physical mechanisms, including non-steady ablation, preheating, and other mechanisms during this phase. The model is validated through simulations under various conditions, demonstrating improved accuracy compared to the classical BD model and the self-similar growth. Furthermore, the model suggests controlling ${{h}_{B}}$ by suppressing the "most dangerous mode", which is influenced by initial perturbations and ablative acceleration history, thus offering novel insights for target manufacturing and pulse optimization near the ignition threshold.