Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 26 for “"Hydrodynamic force"”.
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Experimental Evaluation of Viscous Hydrodynamic Force Models for Autonomous Underwater Vehicles
A comparison of viscous hydrodynamic force models is presented, with application on an autonomous underwater vehicle (AUV). The models considered here are \emph{quasi-steady}, meaning that force is expressed as a function of instantaneous vehicle state. This is in contrast to physical reality, …
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An impulse framework for hydrodynamic force analysis : fish propulsion, water entry of spheres, and marine propellers
… presents an impulse framework for analyzing the hydrodynamic forces on bodies in flow. This general theoretical framework is widely applicable, and it is used to address the hydrodynamics of fish propulsion, water entry of spheres, and the offdesign performance of marine propellers. These …
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Theory for hydrostatic gas journal bearings for micro-electro-mechanical systems
… to analytically calculate the hydrostatic, hydrodynamic, and damping bearing forces. It is found from first principles that the hydrodynamic force due to viscous drag becomes dominant with an L/D<<1 and acts in the opposite direction of the hydrodynamic force due to rotor pumping action.
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Model-based nonlinear control of active tilting-pad bearings
… of feedback control in determining the actuator forces allows for the automatic, continuous adjustment of the pad position during the operation of the rotating machine. In the first part of the dissertation, we develop a nonlinear dynamic model of the active bearing system. The hydrodynamic force …
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Dynamic simulations of particle suspensions subjected to an external electric-field
… electric fields. Such particles experience both hydrodynamic and electrostatic interactions. The hydrodynamic force acting on the particles is determined using the Stokesian dynamics method under the assumption that the Reynolds number is much smaller than 1, while the electrostatic force is …
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Reduced-order modeling and adjoint-based optimization of flows with fluid-structure interactions
… of the flow field as well as the aerodynamic force optimization of 2D flows past oscillating cylinders and NACA0012 airfoils. The adjoint-ROM approach has been proved effective and fast, of which the computational cost saving may make a near-real-time flow control possible. Additionally, the …
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Modular Modification of a Buoyant AUV for Low-Speed Operation
… To maintain depth, they must generate a constant hydrodynamic force which requires that they swim at a constant pitch angle. Although tail fins are the typical mechanism for generating this control moment, they become ineffective at low speeds. To enable an existing AUV to travel at lower speeds, …
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Hydrodynamic and Mass Transport Properties of Microfluidic Geometries
… using simplified transport equations and static force balances. This is possible because the length scales of these geometries ensure low Re conditions approaching the Stokesian limit, where the flow profile is laminar, viscous forces are dominant and inertial forces are negligible. This work …
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Electrohydrodynamic focusing and light propagation in 2-dimensional microfluidic devices for preconcentration of low abundance bioanalytes
This thesis presents work on electrohydrodynamic focusing (EHDF) and photon transmission to aid the development of species preconcentration and identification. EHDF is an equilibrium focusing method, where a target ion becomes stationary under the influence of a hydrodynamic force opposed by an …
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Fluid Mechanics of High Speed Deformable Roll coating. An experimental and theoretical study of film thickness and stability in high speed deformable roll coating flow with Newtonian and non-Newtonian liquids
… The flow is controlled by the combination of hydrodynamic force and elastic deformation effect, which could be complicated by the presence of non-Newtonian fluid. This study necessitated the design and construction of a sophisticated deformable coating rig with the ability to operate over a …
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Analysis of hydrodynamic drag forces acting on suspended fine particle in porous media
… simulations results are used to compute the drag forces experienced by suspended fine particles. The drag force distributions experienced by suspended fine particles of different sizes in various compact granular porous media – ordered (simple cubic (SC), body-centered cubic (BCC), face-centered …
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Particle Dynamics in Inhomogeneous Flow at Moderate to High Reynolds Number
… to obtain an accurate parameterization of the hydrodynamic force acting on a spherical particle in complex inhomogeneous flows at moderate particle Reynolds numbers (Re = 10--600), we develop a DNS technique that resolves the smallest scales in the ambient flow and in the particle wake, and …
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Determining Parameters for a Lagrangian Mechanical System Model of a Submerged Vessel Maneuvering in Waves
… methods and by comparing steady and unsteady hydrodynamic force calculations from the LNMS model against panel code computations for various vessel motions in calm water and in plane progressive waves. Finally, methods for computing physically intuitive components of the model parameters, as …
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Initiation of Particle Movement in Turbulent Open Channel Flow
… proposed, which in addition to the magnitude of hydrodynamic force or flow power, takes into account the duration of the flow event. Two criteria for inception of grain entrainment, namely the critical impulse and critical energy concepts, are proposed and compared. These frameworks adopt a force …
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Hydrodynamically Coupled Shape-Morphing Beams Oscillating in a Viscous Fluid
… fluid-structure interaction (FSI) of a pair of hydrodynamically coupled parallel beams immersed in a quiescent, incompressible, viscous, Newtonian fluid. The beams have two concurrent motions: a rigid oscillation in the vertical direction and a harmonic shape-morphing deformation to an arc of a …
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Simulation of ship-ice collision dynamics.
… has therefore been placed on the development of hydrodynamic and ice force models. Rigorous kinematic constraints at the interaction interface were identified as a critical factor in replicating the dynamic characteristics of prototype collision response. This led to the development of techniques …
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Modeling the Motion of Solid Objects Immersed in Viscoelastic Fluids
… between the particle trajectory and the force exerted on it by the surrounding fluid at low Weissenberg numbers, as well as how an inverse relationship can be determined and used to analyze the trajectory of a particle propelled by some external force. Potential applications for this …
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Microfluidic processes to create structured microparticle arrangements and their applications
… Particles are guided and assembled into wells by hydrodynamic force associated with fluid flow through pores in microwell. Iteration of assembly and washing steps ensures high-throughput, large-scale particle arrangement with high yields on filling and capturing. Scaling theory allows for the …
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Hydrophobic Forces in Free Thin Films of Water in the Presence and Absence of Surfactants
… different system were studied to investigate the forces interacting in thin liquid films. In the former, direct force measurements were conducted with bitumen-coated mica surfaces using a Mark IV surface force analyzer. Besides long-range electrostatic repulsive forces at separation distances …
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Rheology of polyelectrolyte multilayer modified suspension
… is a very sensitive measure for the relevant forces that govern the rheology, and hence the experiments identify that at high shear stresses hydrodynamic forces dominate the interparticle interactions. Moreover, the strength of the hydrodynamic force depends again on the terminating …
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