Masters Thesis

A combined numerical and laser doppler anemometry characterization of water flow over a circular cylinder in a channel

In this paper, a numerical model of simulating water flow velocity through a channel with a circular cylinder is created, and the simulation is verified with a comparison to laser Doppler anemometry experimental results with uncertainty analysis. The experimental results are obtained using laser Doppler anemometry to determine the horizontal velocity of the fluid flow from the bottom of the water channel to the top, creating a velocity profile at that particular distance from the channel inlet. Several velocity profiles are captured using this method down the entire length of the experimental channel. The numerical analysis is performed using ANSYS Fluent with varying grid size and using k-ε and SST k-ω turbulence models. The simulation results show that the numerical models have desirable convergence properties, implying that a smaller grid size results in better accuracy. It is also shown that SST k-ω results conformed similarly to the k-ε results, as evidenced by both their Validation Comparison Errors ranging between 0.0005 and 0.083. As a secondary analysis, the drag coefficient is calculated based on the numerical results and is found to be 1.192 using the SST k-ω model and 1.22 using the k-ε model; however, a comparison with the control volume calculation shows that k-ε suffers in performing near-wall calculations. These results compare well between the models, further indicating that ANSYS Fluent is an effective calculation tool.

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