Naval Postgraduate School

Double-Diffusive Convection in Rotational Shear Naval Postgraduate School

This book examined the effect a variety of induced velocity shears had on salt finger formation. Two harmonic, single frequency velocity profiles were utilized under varied shear strength and angular frequency. The third multi-frequency experiment employed a stochastic shear wave field. This model used frequencies that conformed to the GM spectral model for internal waves with an initial random phase distribution, modeling an environment representative of typical oceanic conditions. These shear profiles were incorporated in a double diffusion numerical model. The model resolved the formation and development of salt fingers and recorded the resultant salt and heat fluxes. The results showed that shear strength and direction influenced salt finger diffusion rates and structure alignment. For a stochastic environment, this effect is driven largely by near-inertial motions. The low-frequency waves align salt fingers, and the wax and wane of these waves impact the instantaneous diffusive rates. These internal waves reduced the salt and heat flux to that representative for un-sheared two-dimensional double diffusion simulation.