# Fluid rope trick investigated

Original entry by Joerg Fritz, AP225 Fall 2009

## Contents

## Source

"Fluid rope trick investigated"

L. Mahadevan, W.S. Ryu, A.D.T. Samuel: *Nature*, 1998, 392, pp 140 to 141

## Keywords

Buckling, Viscosity, Surface tension, Instability

## Summary

This paper studies a very rich problem at the interface between fluid dynamics and classical mechanics that can be observed in thousands of household every morning. If honey is poured from a sufficient height, it approaches the morning toast as a thin filament which twists and whirls steadily even if the pouring hand is completely static. This can be explained by the theory of buckling with very simple scaling laws.

## The Math

What sets the speed with which the honey rotates? We could imagine up to six parameters that could have an influence on the rotation speed. On an intuitive basis it could depend on

## Conclusion

working on it