Experimental Simulation of Density-Driven Thunderstorm Downbursts

Evaporative cooling of the precipitation within the thunderstorm cloud results in the formation of a mass of cold and dense air which moves toward the ground and after impingement turns into strong radial winds near the surface. In this study, an experimental approach was taken to investigate the downbursts. The two-fluid model was used, and the various features of the experimental setup of previous researchers were modified to incorporate the specifications of natural downbursts. First, two new release cylinders were manufactured and their capabilities in producing repeatable and symmetric outflows were examined. Then, the effects of cylinder wall design, density difference and release height on the downbursts were investigated. For the first time, the translation of storm and the velocity field of the ambient environment were considered in the experimental simulations of downbursts based on a density-driven model. In this regard, a hydraulic flume equipped with a trolley was employed