# Anisotropic super-attenuation of capillary waves on driven glass interfaces

## TL;DR

This study reveals that capillary waves on driven glass interfaces exhibit anisotropic super-attenuation, leading to reduced surface roughness that records the flow direction, with attenuation following a power law related to drawing stress.

## Contribution

It demonstrates the anisotropic super-attenuation of capillary waves on glass interfaces and links roughness reduction to drawing stress in a power-law manner.

## Key findings

- Surface roughness is reduced below thermodynamical limits.
- Attenuation follows a power law with drawing stress.
- Surface retains structural memory of flow direction.

## Abstract

Metrological AFM measurements are performed on the silica glass interfaces of photonic band-gap fibres and hollow capillaries. The freezing of attenuated out-of-equilibrium capillary waves during the drawing process is shown to result in a reduced surface roughness. The roughness attenuation with respect to the expected thermodynamical limit is determined to vary with the drawing stress following a power law. A striking anisotropic character of the height correlation is observed: glass surfaces thus retain a structural record of the direction of the flow to which the liquid was submitted.