Thermally Forced Low Froude Number Flow past Three-Dimensional Obstacles

Abstract

Abstract The present study extends the discussion of the flow of a density-stratified fluid past three-dimensional obstacles for Froude number O(1) to flows past an isolated obstacle with heated/cooled surface. The study focuses on a response of thermally forced stratified flows representative of mesoscale flows past mountainous islands such as Hawaii or Taiwan. In order to minimize the span of the parameter space, uniform ambient wind and stratification, axially symmetric bell-shaped hills with moderate slopes representative of mesoscale mountains, and a simple thermal forcing function that mimics natural effects over mountainous islands are assumed. The earth's rotation, surface friction, viscosity, dissipation, and moisture are neglected. With these simplifications flows can be characterized with two parameters: the Froude number and a characteristic scale of thermal forcing (defined later in this paper). The principal question addressed in this study is under what circumstances will a transition occur...