# Origin of lobe and cleft at the gravity current front

## TL;DR

This paper investigates the formation of lobes and clefts at gravity current fronts, demonstrating that Rayleigh-Taylor instability explains their origin and confirming theoretical predictions with numerical simulations.

## Contribution

It provides a detailed analysis linking RTI to the formation of lobes and clefts, validating semi-infinite RTI model predictions through 3D simulations.

## Key findings

- RTI determines the formation of lobes and clefts.
- Spanwise wavenumber depends on Prandtl number.
- Wavenumber scales with Grashof number as 1/3.

## Abstract

In this paper the Rayleigh-Taylor instability (RTI) along the density interfaces of gravity-current fronts is analyzed. Both the location and the spanwise wavenumber of the most unstable mode determined by the local dispersion relation agree with those of the strongest perturbation obtained from numerical simulations, suggesting that the original formation mechanism of lobes and clefts at the current front is RTI. Furthermore, the predictions of the semi-infinite RTI model, i.e. the original dominating spanwise wavenumber of the Boussinesq current substantially depends on the Prandtl number and has a 1/3 scaling law with the Grashof number, are confirmed by the three-dimensional numerical simulations.