Electronic Thesis and Dissertation Repository

Degree

Master of Engineering Science

Program

Mechanical and Materials Engineering

Supervisor

Dr. Eric Savory

Abstract

A series of Large Eddy Simulations using an atmospheric meteorological cloud model have been used to investigate the important geometric and thermal parameters that influence a thunderstorm downburst outflow, as it pertains specifically to the idealized cooling source model. A separate set of Large Eddy Simulations make use of the same idealized cooling source model, in a realistic atmospheric base state using real field sounding data, in an attempt to make a quantifiable comparison to a downburst from a full cloud simulation. Randomness has been added to the cooling source forcing function to mimic the thermal variation in a real thunderstorm. It is found that the initial source parameters of the cooling source have a strong influence on the downburst outflow wind field metrics. It is also shown that scaling such events in size and height above the ground results in outflow wind field quantities that are comparable when using a scaling method for liquid drop release experiments. Additionally, it is found that using the cooling source model in a realistic atmospheric base state results in outflow wind characteristics that are more typical of sophisticated cloud models. Peak outflow wind speeds occur at a comparable height and overall magnitude, and the vertical profile of radial wind speed takes on a similar shape.