Date of Graduation

5-2022

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Engineering (PhD)

Degree Level

Graduate

Department

Civil Engineering

Advisor/Mentor

R. Panneer Selvam

Committee Member

Micah Hale

Second Committee Member

Ernie Heymsfield

Third Committee Member

Mark E. Arnold

Keywords

Atmospheric Sciences, CFD Flow Validation, CFD Tornado Simulation, Experimental Comparison, Fluid Mechanics, Tornado pressures on building, Tornado Vortex Modeling, Vortex Touchdown

Abstract

Structural failure of low-rise buildings is the root cause of higher number of casualties, death tolls and economic losses at the place of occurrence of tornadoes. Proper design of low-rise buildings in tornado-prone areas require accurate estimation of tornado-induced wind loads; however, exhaustive research to estimate the wind loads reliably on buildings during tornadic events is still lacking. Several studies have been carried out to investigate the magnitude of forces induced by tornado winds on buildings from experimental as well as computational side. However, the wind pressures obtained on the building from different experimental studies have shown significant variation from one study to another. Similarly, the wind pressures on the building from CFD simulation of tornado vortex often lacks comparison and/or validation with experimental data. Even the modeling of CFD tornado chamber and CFD flow validation is fraught with several challenges such as requirements of high-performance (or supercomputing) resources and lack of guidelines for validation of wind field of tornado vortex from CFD model.

Thus, in this work, a simple yet an effective CFD tornado simulator model is developed, which provides comparable results with experiment without the necessity of supercomputing resources. This work also identifies and proposes four important features of tornado vortex (i.e., touchdown swirl ratio, core radius, the maximum tangential velocity & the elevation of maximum tangential velocity) including the ground pressure profile for validation of wind field obtained from CFD model. A comparative analysis of the four important vortex features from different tornado chambers and different work of literature is also presented. Lastly, the pressures induced by tornado vortex from CFD model on the building is validated with TTU experimental datasets. Furthermore, a detailed analysis on the effect of size of building, flow structure and Reynolds number of vortex on the induced wind pressures on the building is also presented.

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