# Axisymmetric internal wave transmission and resonance in non-linear stratifications

## TL;DR

This paper investigates how non-linear and two-layer stratifications affect axisymmetric internal wave transmission and resonance, revealing maximum transmission near evanescent frequencies and resonant effects that enhance transmission in confined waves.

## Contribution

It introduces a novel wave generator setup to study axisymmetric internal wave transmission in non-linear stratifications both theoretically and experimentally.

## Key findings

- Maximum transmission occurs near evanescent frequencies.
- Resonant effects significantly enhance transmission in confined waves.
- Real-world ocean stratification can exhibit these transmission phenomena.

## Abstract

To date, the influence of non-linear stratifications and two layer stratifications on internal wave propagation has been studied for two-dimensional wave fields in a cartesian geometry. Here, we use a novel wave generator configuration to investigate transmission in non-linear stratifications of axisymmetric internal wave. Two configurations are studied, both theoretically and experimentally. In the case of a free incident wave, a transmission maximum is found in the vicinity of evanescent frequencies. In the case of a confined incident wave, resonant effects lead to enhanced transmission rates from an upper layer to layer below. We consider the oceanographic relevance of these results by applying them to an example oceanic stratification, finding that there can be real-world implications.