Image based computational fluid dynamics modeling to simulate fluid flow around a moving fish

Image based computational fluid dynamics modeling to simulate fluid flow around a moving fish." MS ii To Angela iii It seems to me that we all look at Nature too much, and live with her too little. Oscar Wilde De Profundis iv ACKNOWLEDGMENTS I would like to thank Justin Garvin for all of the support he has given me over the last few years. He is one of the best mentors I have ever had, and I can " t say enough good things about him. I " d like to thank Angela Brown for always being there. We became study partners our first semester of college, and I consider her my best friend. I " d like to thank Larry Weber, who even though he is a very busy guy, always seems to have time to chat and get to know his students. And finally, I " d like to thank the Hydro Research Foundation for funding this project. This would not have been possible without their support. v ABSTRACT Understanding why fish move the way in which they do has applications far outside of biology. Biological propulsion has undergone millions of years of refinement, far outpacing the capabilities of anything created by man. Research in the areas of unsteady/biological propulsion has been increasing in the last several decades with advances in technology. Researchers are currently conducting experiments using pitching and heaving airfoils, mechanized fish, and numerical fish. However, the surrogate propulsors that are being used in experiments are driven analytically, whereas in this study, a method has been developed to exactly follow the motion of swimming fish. The research described in this thesis couples the image analysis of swimming fish with computational fluid dynamics to accurately simulate a virtual fish. Videos of two separate fish swimming modes were analyzed. The two swimming modes are termed " free-stream swimming " and the " Kármán gait ". Free-stream swimming is how fish swim in a section of water that is free of disturbances, while Kármán gait swimming is how fish swim in the presence of a vortex street. Each swimming mode was paired with two simulation configurations, one that is free of obstructions, and one that contains a vortex street generating D-section cylinder. Data about the efficiency of swimming, power output, and thrust production were calculated during the simulations. The results showed that the most efficient mode of swimming was …