A Numerical Study of the Kelvin-Helmholtz Instability on Large Amplitude Internal Waves

Amber Sallerson, University of North Carolina - Chapel Hill

Internal gravity wave dynamics in stratified fluids are recently experiencing increased attention due in part to the role played by these waves in environmental issues such as near-coastal dynamics; however, great difficulties arise in collecting data in either field or lab experiment and thus numerical simulations can be very valuable in shedding light on observed phenomenon. A conservative projection method for the variable density Euler equations is implemented to simulate numerically the generation and propagation of internal solitary waves. By using parameters and dimensions from a set of laboratory experiments involving fresh water and brine separated by a thin diffused interface, the code is validated against experimental data as well as theoretical results for regimes that include near maximum amplitude waves. The wave-induced shear instabilities that can be observed in these regimes are captured by the numerical simulations, and are studied in detail by initializing the dynamics with traveling wave solutions computed through an iterative scheme.

Abstract Author(s): Amber Sallerson and Roberto Camassa