Date of Award
Level of Access Assigned by Author
Master of Science in Mechanical Engineering (MSME)
Second Committee Member
Third Committee Member
Additional Committee Members
Impulsively started, low-speed, incompressible jets observed in nature, are commonly found as starting flows through a moving valve. Similar flows are found in the human heart where blood is transported from the left atrium, through the mitral valve, and into the left ventricle. During this process, a vortex is formed around the lip of the moving valve before propagating into the left ventricle. We use a sharp-interfaced, immersed boundary method based, CFD solver to run a series of numerical simulations to investigate the vortex dynamics of starting flows through an axisymmetric nozzle with time varying exit geometry. The incompressible fluid field, contained within a cylindrical tank, is subjected to a temporally specified volumetric flow rate, held at the nozzle inlet, while the nozzle is treated as a rigid body with motion independent of fluid forces. We show that nozzle motion affects both vortex formation time and pinch-off time, as well as the size, circulation, and energy associated with the leading vortex ring. By parametrically ranging over a variety of prescribed flow rates and exit diameter frequencies, the independent contributions of the nozzle motion on the developing vortex structures and the distinctive characteristics of their formation processes are presented and subsequently assessed.
Farrar, Lucas I., "Numerical Investigation of Vortex Formation with Application to Left Ventricle Filling" (2017). Electronic Theses and Dissertations. 2674.