Impinging jet simulation of stationary downburst flow over topography

M.S. Mason, G.S. Wood and D.F. Fletcher

Abstract

A non-translating, long duration thunderstorm downburst has been simulated experimentally and numerically by modelling a spatially stationary steady flow impinging air jet. Velocity profiles were shown to compare well with an upper-bound of velocity measurements reported for full-scale microbursts. Velocity speed-up over a range of topographic features in simulated downburst flow was also tested with comparisons made to previous work in a similar flow, and also boundary layer wind tunnel experiments. It was found that the amplification measured above the crest of topographic features in simulated downburst flow was up to 35% less than that observed in boundary layer flow for all shapes tested. From the computational standpoint we conclude that the Shear Stress Transport (SST) model performs the best from amongst a range of eddy-viscosity and second moment closures tested for modelling the impinging jet flow.

Key Words

downburst; speed-up; topography; impinging jet.

Address

M.S. Mason; School of Civil Engineering, University of Sydney, Sydney, NSW 2006, Australia G.S. Wood; Cermak Peterka Petersen, Pty. Ltd., St. Peters, NSW 2044, Australia D.F. Fletcher; School of Chemical and Biomolecular Engineering, University of Sydney, Sydney, NSW 2006, Australia

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