Date of Award
Fall 2015
Project Type
Dissertation
Program or Major
Mechanical Engineering
Degree Name
Doctor of Philosophy
First Advisor
John P. McHugh
Second Advisor
John P. McHugh
Third Advisor
Gregory P. Chini
Abstract
A horizontal distributed vortex in a stratified fluid is treated using direct numerical simulations. The strength of the vortex is uniform but antisymmetric about the centerline such that the total circulation is zero, as with airplane wings. This distributed vortex allows the density field and velocity field to evolve together, as happens in real flows behind lifting surfaces. The numerical approach is spectral in space with periodic horizontal directions and a projection method in time using the 3rd order Adams-Bashforth method. The primary parameter is the Froude number. For large Froude number, the distributed vorticity quickly rolls up and forms a vortex pair, approximately matching cases initiated as a fully-developed vortex pair. For small Froude number, both cases disintegrate into internal waves. It is found here that the critical Froude number with a distributed vortex is much larger than previously thought. The results also show that distributed vortex exhibits a strong vertical oscillation with frequency that is approximately the buoyancy frequency N. Late in the simulations, the flow degenerates into small-scale motion.
Recommended Citation
Shaw, Surupa, "A Distributed Vortex in Stratified Flow" (2015). Doctoral Dissertations. 2218.
https://scholars.unh.edu/dissertation/2218