Modulation Of Hydrodynamic Forces On Oscillating Submerged Structures In Viscous Fluids

The study of the dynamical behavior of flexible submerged cantilever-like structures subjected to underwater vibration is of primary importance in a wide range of scientific and engineering fields. In the context of such applications, the performance of submerged devices primarily depends on the hydrodynamic forces experienced by the submerged structure resulting from the fluid-structure interactions. In turn, such forces are correlated to power dissipation occurring during underwater oscillations. The added mass and hydrodynamic damping effect that arise due to the interaction between the fluid and the structure are of practical relevance to design, fabrication, and control of devices operating in viscous fluids. Modulation of the forces and dissipated power by manipulating the hydrodynamics in the vicinity of the structure can thus improve the performance of these devices. In this dissertation, we discuss several fluid-structure interaction problems concerning oscillating submerged bodies in viscous fluids with the overarching target ofmodulating hydrodynamic forces and power dissipation for optimal dynamic behavior. Towards this goal, we propose the novel paradigm of "shape-morphing" structures, whereby time-varying structural deformations are considered to manipulate vortex shedding and viscous forces. For a comprehensive set of vibration scenarios, including flexural and torsional vibrations in an unbounded fluid, as well as transverse oscillations in the vicinity of a solid wall, we conduct a thorough numerical and semi-analytical study to estimate the forces applied to the submerged structure and characterize the forces in the form of a manageable hydrodynamic function depending on different governing parameters. The completed research activity thus elucidates the potential of the novel shape-morphing strategy to control and modulate hydrodynamic forces and power dissipation and its applicability in different research and application fields. The capability to adapt to varying dynamical conditions and complex vibration scenarios will make this novel fluid-structure interaction control paradigm an attractive solution for applications in atomic force microscopy, micromechanical sensors and actuators, piezoelectric fan systems, biomimetic robotic propulsion, and smart material-based energy harvesting devices.

Level thesis:degree_level

Doctorate Degree

Year dc:date.issued

2018

Author dc:creator

• Ahsan, Syed N.

Advisor dc:contributor.advisor

• Aureli, Matteo

Committee members dc:contributor.committeemember

• Liao, Yiliang
• Tung, Ryan C.
• Shen, Yantao
• Vasquez, Victor R.

• actuator
• Fluid mechanics
• Fluid-structure interactions
• sensor
• Underwater Oscillation
• vibration

Statement dc:rights

• Creative Commons Attribution 4.0 United States

Handle dc:identifier.uri

http://hdl.handle.net/11714/4515

OAI identifier oai:identifier

oai:scholarwolf.unr.edu:11714/4515