|Author's Email Address
||This thesis had been viewed 5385 times. Download 833 times.|
||Mechanical and Electro-Mechanical Engineering|
|Type of Document
||Investigation of cavitating flow by lagrangian coherent structure|
|Date of Defense
||Turbulent cavitating flows are ubiquitous in our daily life and technologies, which will induce the noises, material removal, and efficiency reduction of the flow machinery. As the result, it is important to investigate the flow structures of the cavitating flow to predict its dynamical behaviors effectively. In the present study, we utilize the volume of fraction techniques to time-dependent turbulent cavitating flows.|
Lagrangian Coherent Structures (LCS) have been developed to highlight the flow structures recently. It is a trajectory-basedapproach from a Lagrangian perspective by considering the fluid as a dynamical system of fluid particles rather than a continuum. This method is frame-independent and more useful to capture the dynamical features of the flows, which can be missed in the traditional Eulerian analyses based on the velocity or vorticity fields.
This dissertation utilizes the finite-time Lyapunov exponent(FTLE) and LCS to get a better understanding of the flow dynamics and underlying physics of the simulated cavitating flows for different representative phenomena during the corresponding stages. It is found that LCS can capture the re-entraint jet front and also indicate that fluid around lower surface could be attracted to the upper surface of the hydrofoil when the induced cavity grows around the trailing edge. This dissertation also analyzes the complicated flow interaction around the trailing edge when the multiple circulation and cavitation regions are formed by particle tracking method.
||Kuang-Chuan Lin - chair|
Fu-Ling Yang - co-chair
Yang-Yao Niu - co-chair
Chien-Chou Tseng - advisor
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|Date of Submission