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You searched for +publisher:"Virginia Tech" +contributor:("Hajj, Muhammad Ramiz"). One record found.

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1. Hussein, Ahmed Abd Elmonem Ahmed. Dynamical System Representation and Analysis of Unsteady Flow and Fluid-Structure Interactions.

Degree: PhD, Engineering Mechanics, 2018, Virginia Tech

We present modeling approaches of the interaction between flying or swimming bodies and the surrounding fluids. We consider their stability as they perform special maneuvers. The approaches are applied to rotating blades of helicopters, fish-like robots, and micro-air vehicles. We develop and validate a new mathematical representation for the flow generated by moving or deforming elements. We also assess the effects of fast variations in the flow on the stability of a rotating helicopter blade. The results point to a new stable regime for their operation. In other words, the fast flow variations could stabilize the rotating blades. These results can also be applied to the analysis of stability of rotating blades of wind turbines. We consider the effects of flexing a tail on the propulsive force of fish-like robots. The results show that adding flexibility enhances the efficiency of the fish propulsion. Inspired by the ability of some birds and insects to transition from hovering to forward motion, we thoroughly investigate different approaches to model and realize this transition. We determine that no simplification should be applied to the rigorous model representing the flapping flight in order to model transition phenomena correctly. Finally, we model the forward-swim dynamics of psciform and determine the condition on the center of mass for which a robotic fish can maintain its stability. This condition could help in designing fish-like robots that perform stable underwater maneuvers. Advisors/Committee Members: Hajj, Muhammad Ramiz (committeechair), Woolsey, Craig A. (committee member), Canfield, Robert Arthur (committee member), Ragab, Saad A. (committee member).

Subjects/Keywords: Finite-State Unsteady Aerodynamics; Lagrangian; Point Vortices; Flutter; Aeroelasticity; Finite Element Method; Flexibility; Hydroelasticity; Nonlinear Time-Periodic Dynamics; Floquet Analysis; Optimal Control

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Hussein, A. A. E. A. (2018). Dynamical System Representation and Analysis of Unsteady Flow and Fluid-Structure Interactions. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/85626

Chicago Manual of Style (16th Edition):

Hussein, Ahmed Abd Elmonem Ahmed. “Dynamical System Representation and Analysis of Unsteady Flow and Fluid-Structure Interactions.” 2018. Doctoral Dissertation, Virginia Tech. Accessed December 10, 2019. http://hdl.handle.net/10919/85626.

MLA Handbook (7th Edition):

Hussein, Ahmed Abd Elmonem Ahmed. “Dynamical System Representation and Analysis of Unsteady Flow and Fluid-Structure Interactions.” 2018. Web. 10 Dec 2019.

Vancouver:

Hussein AAEA. Dynamical System Representation and Analysis of Unsteady Flow and Fluid-Structure Interactions. [Internet] [Doctoral dissertation]. Virginia Tech; 2018. [cited 2019 Dec 10]. Available from: http://hdl.handle.net/10919/85626.

Council of Science Editors:

Hussein AAEA. Dynamical System Representation and Analysis of Unsteady Flow and Fluid-Structure Interactions. [Doctoral Dissertation]. Virginia Tech; 2018. Available from: http://hdl.handle.net/10919/85626

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