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Full-Text Articles in Engineering
Experimental Investigation Of The Vortex-Induced Vibration Response Of A Flexibly-Mounted Rigid Cylinder In The Shear-Thinning And Inertial-Viscoelastic Flow Regimes, Pieter Boersma
Doctoral Dissertations
Flexible or flexibly-mounted structures with bluff cross-sections in flow can shed vortices at frequencies that increase with increasing flow velocity. When this shedding frequency is equal to the structure's natural frequency, the structure can oscillate. This is called vortex-induced vibrations (VIV). VIV is present in multiple fluid-structure interaction (FSI) systems which can be found in industrial, medical, and engineering applications. These oscillations can be desirable or undesirable, so understanding the physics behind this phenomenon is important. This work seeks to investigate experimentally the VIV response in the inertial-viscoelastic regime where fluid inertia and elasticity influence the system. The subcritical Newtonian …
Experimental Study Of Viscoelastic Fluid-Structure Interactions, Anita Anup Dey
Experimental Study Of Viscoelastic Fluid-Structure Interactions, Anita Anup Dey
Doctoral Dissertations
It is well known that when a flexible or flexibly-mounted structure is placed perpendicular to a Newtonian fluid flow, it can oscillate due to the shedding of vortices at high Reynolds numbers. Unlike Newtonian fluids, viscoelastic fluid flow can become unstable even at infinitesimal Reynolds numbers due to a purely elastic flow instability occurring at large Weissenberg numbers. This thesis focuses on exploring the mechanisms of viscoelastic fluid-structure interactions (VFSI) through experimental investigations on several different combinations of flexible and flexibly-mounted circular cylinders, micro and macro-scale cantilevered beams and viscoelastic fluids such as wormlike micelle solutions and polymer solutions. VFSI …
Experimental Study On Viscoelastic Fluid-Structure Interactions, Anita Anup Dey
Experimental Study On Viscoelastic Fluid-Structure Interactions, Anita Anup Dey
Masters Theses
It is well known that when a flexible or flexibly-mounted structure is placed perpendicular to the flow of a Newtonian fluid, it can oscillate due to the shedding of separated vortices at high Reynolds numbers. If the same flexible object is placed in non-Newtonian flows, however, the structure's response is still unknown. The main objective of this thesis is to introduce a new field of viscoelastic fluid-structure interactions by showing that the elastic instabilities that occur in the flow of viscoelastic fluids can drive the motion of a flexible structure placed in its path. Unlike Newtonian fluids, the flow of …
Reduced Order Fluid-Structure Interaction Models For Thin Shells With Non-Zero Gaussian Curvatures To Understand The Response Of Aneurysms To Flow, Gary Han Chang
Doctoral Dissertations
In this thesis, a reduced-order model is constructed to study the physiological flow and wall shear stress conditions for aneurysms. The method of local proper orthogonal decomposition (POD) is used to construct the reduced-order modes using a series of CFD results, which are subsequently improved using a QR-factorization technique to satisfy the various boundary conditions in physiological flow problems. This method can effectively construct a computationally efficient physiological model, which allows us to examine the fluid velocities and wall shear stress distributions over a range of different physiological flow parameters. Aneurysms are the dilation, bulging, or ballooning-out of part of …
A Nonlinear Model For Wind-Induced Oscillations Of Trees, Lakshmi Narayanan Ramanujam
A Nonlinear Model For Wind-Induced Oscillations Of Trees, Lakshmi Narayanan Ramanujam
Masters Theses 1911 - February 2014
Ambient wind causes trees to oscillate. Wind-induced oscillations of trees constitute a fluid-structure interaction problem, which has been studied by many researchers from various points of view. However, there is yet a lot to be done. From an engineering point of view, the complex structure of trees, which are very different from man-made structures, as well as the highly nonlinear interaction between wind and tree, makes it a challenging task to predict the amplitude and frequency of the resulting oscillations. From a biological point of view, the influence of wind on photosynthesis as well as the growth and death of …