Proposed large-scale modelling of the transient features of a downburst outflow

W. E. Lin, L. G. Orf, E. Savory and C. Novacco

Abstract

A preceding companion article introduced the slot jet approach for large-scale quasi-steady modelling of a downburst outflow. This article extends the approach to model the time-dependent features of the outflow. A two-dimensional slot jet with an actuated gate produces a gust with a dominant roll vortex. Two designs for the gate mechanism are investigated. Hot-wire anemometry velocity histories and profiles are presented. As well, a three-dimensional, subcloud numerical model is used to approximate the downdraft microphysics, and to compute stationary and translating outflows at high resolution. The evolution of the horizontal and vertical velocity components is examined. Comparison of the present experimental and numerical results with field observations is encouraging.

Key Words

downburst; microburst; outflow; localized high-intensity wind; wind tunnel; slot jet; wind loading; subcloud numerical model; cooling source.

Address

W. E. Lin; Department of Mechanical & Materials Engineering, The University of Western Ontario, London, Ont., N6A 5B9, Canada L. G. Orf; Department of Geography (Meteorology), Central Michigan University, Mount Pleasant, MI, 48859, USA E. Savory and C. Novacco; Department of Mechanical & Materials Engineering,The University of Western Ontario, London, Ont., N6A 5B9, Canada

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