Matthew Mason

BE, MSCE
PhD Research Student
Environmental Fluids Group

School of Civil Engineering, Room 342
Phone: +61 2 9351 2457
Fax: +61 2 9351 8609
Email: M.Mason@civil.usyd.edu.au

Research project - Modelling of Severe Thunderstorm Winds

Supervisor: Dr Graeme Wood
Associate Supervisor: Adjunct Professor David Fletcher (Chemical Engineering)

Every year in Australia convectively driven wind storms cause millions of dollars in structural damage to domestic housing and low-rise structures. The nature of these wind storms is very localised and can be very severe. The winds from convective thunderstorms are very different to the Atmospheric Boundary Layer (or synoptic) winds currently designed for in AS1170.02 and thus it may be the case that they are inappropriately designed for.

In the first part of this research project we have used a laboratory scale impinging jet to model the bulk characteristics of a jet of air impinging a solid boundary – analogous to a downdraft impinging the ground. This modelling technique is a crude engineering representation of the physical process that occurs during thunderstorm downburst wind events, but allows general conclusions to be drawn about this type of flow. We have modelled the influence of simulated downdraft impingement angle, ground surface roughness, and the presence of scaled topographic features.

The second component of this research project was to implement a refined dry, non-hydrostatic, high resolution, thunderstorm outflow model to study the low level wind structure of isolated thunderstorm outflow events. The main objectives were to produce vertical wind profiles, and determine the influence of low level features such as topography, surface roughness and ambient wind conditions on these profiles. In contrast to the first part of this research, these simulations were conducted at full-scale dimensions, and have allowed analysis of the highly variable temporal characteristics of the high wind speed region associated with the outflow's gust front.

Numerically simulated downburst potential temperature and wind field.

Selected publications

Mason, M.S., Wood, G.S., Fletcher, D.F., 2008, Numerical simulation of downburst winds, Submitted to Journal of Wind Engineering and Industrial Aerodynamics.
Mason, M.S., Wood, G.S., Fletcher, D.F., 2007, Impinging jet simulation of stationary downburst flow over topography. Wind and Structures 10, 437-462.
Mason, M.S., Wood, G.S., Fletcher, D.F., 2007, A simple atmospheric downburst model for wind engineering application. Proceedings of the 12th International Conference on Wind Engineering, Cairns.
Mason, M.S., Letchford, C.W., & James, D.J., 2005, Pulsed wall jet simulation of a stationary thunderstorm downburst, Part A: Physical structure and flow field characterization. Journal of Wind Engineering and Industrial Aerodynamics, 93, 557-580.
Mason, M.S., Wood, G.S., 2005, Influence of jet inclination on structural loading in an experimentally simulated microburst, Proceedings of The 6th Asia-Pacific Conference on Wind Engineering, Seoul, Korea.
Mason, M.S., Wood, G.S., “Loading of a tall building in a simulated downburst wind field,” 11th Australasian Wind Engineering Society Workshop, Darwin, 2004.
Mason, M.S., Letchford, C.W., & Wood, G.S., 2004, Physical simulation of thunderstorm downbursts for wind engineering application. Proceedings of the International Conference on Storms, Brisbane.

Learning and Teaching

CIVL2611 Fluid Mechanics
CIVL3612 Fluids and Environmental Engineering

Thunderstorm damage