Water surface profile computation around square blocks by imaginary representation of the obstructions in the shallow water equations

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2021-7

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Hofioni, Sayed Omar

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Depth integrated shallow flow equations can be solved easily over large domains to provide flood inundation maps. However, there may be numerous natural or artificial obstructions that increase resistance to flow due to drag forces induced on the submerged volumes. It is possible to numerically solve the governing equations on a suitable grid system for the flow field around such obstructions and determine the flow depths. But, when the number of obstructions increases with arbitrary size and distribution, such a detailed numerical solution is unfeasible. In this study, a new technique is proposed to reduce the geometric complexity and computational work when the number of obstructions is large. The computational grid is generated without the obstructions, but the numerical solution is achieved by introducing the expected drag forces in the governing equations to represent the imaginary obstructions. This technique simplifies the computational grid as if there is nothing other than water in the computational domain. However, hydrodynamic consequences of obstructions are correctly reproduced in the 2D free surface profile. vi Flow around a single square block and three-square blocks in a side-by-side configuration are considered as test cases. Experimental data describing water surface profiles are collected for different flow conditions. Numerical solutions are obtained with the block and with the imaginary block. Results are compared to experimental data, and it is found that the present ‘imaginary block’ approach produces successful solutions without any loss of information.

Subject Keywords

Shallow flows, Water surface profile, Flood inundation, Drag force

URI

https://hdl.handle.net/11511/91483

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

S. O. Hofioni, “Water surface profile computation around square blocks by imaginary representation of the obstructions in the shallow water equations,” M.S. - Master of Science, Middle East Technical University, 2021.