Electronic Thesis and Dissertation Repository

Degree

Master of Engineering Science

Program

Civil and Environmental Engineering

Supervisor

Bitsuamlak, Girma

Abstract

There are difficulties in making a common interpretation of results of similar experiments done in different experimental tornado simulation facilities. This is primarily because of the differences in vortex generation mechanisms utilized as well as geometric differences in these facilities. Therefore, in an attempt to facilitate a universal interpretation of results, a generic numerical tornado model, representing the three major existing experimental tornado simulators, is developed in this study. The three experimental simulators in consideration are VorTECH at Texas Tech University, Tornado Simulator at Iowa State University and WindEEE Dome at Western University as representatives of “Ward” type, “top-down” type and “3-D wind chamber” type facilities, respectively.

First, the three experimental facilities and their corresponding flow-fields are replicated using CFD simulations and then the differences and similarities in their flow-fields are identified. It is demonstrated that it is possible to link different experimental facilites through a generic numerical model by characterizing a tornado-like vortex using parameters strictly obtained from the flow-field, as opposed to the common practice of using geometric dimensions of the experimental facilities to extract these parameters. This part of the study requires an extensive parametrization to characterize these vortices, hence computationally effective and reasonably accurate Reynolds Stress Model (RSM) is used. Further, the potential application of this generic numerical model to bluff-body aerodynamics and wind load evaluation is demonstrated by using a more accurate Large Eddy Simulation technique. While the results show some minor but explainable discrepancy with experimentally obtained data, the proposed generic numerical model displays a promise towards its application for preliminary tornadic aerodynamic data generation.

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