Green and renewable energy technologies are becoming more and more necessary as demand for energy grows exponentially around the world. Recently, there has been increased interest in using marine hydrokinetic turbines...
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Green and renewable energy technologies are becoming more and more necessary as demand for energy grows exponentially around the world. Recently, there has been increased interest in using marine hydrokinetic turbines to generate energy from ocean currents and tidal flows. The blades of these turbines are slender and are subjected to large, dynamic fluid forces; for that reason they are typically constructed from fiber-reinforced composites. The bend-twist deformation coupling behavior of these materials can be hydroelastically tailored such that the pitch angle of the blades will passively change to adapt to the surrounding flow, creating an instantaneous reaction that can improve system performance over the expected life of the turbine. Potential benefits of this passive control mechanism include increased lifetime power generation, reduced hydrodynamic instabilities, and improved load shedding and structural performance. There are practical concerns, however, that increase the complexity of the design of these bend-twist coupled blades. Large inflow variations in viable locations for turbine implementation combined with system component limitations such as restrictions on the generator and maximum rotational speed require consideration of practical and site-specific constraints. Using a previously validated boundary element method-finite element method solver, this work presents a numerical investigation into the capabilities of passive pitch adaptation under both instantaneous and long-term variable amplitude loading to better describe potential benefits while considering practical design and operational restrictions
In this paper, we present some recent studies on fluid-structure interaction problems in the presence of free surface flow. We consider the dynamics of boats simulated as rigid bodies. Several hydrodynamic models are ...
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In this paper, we present some recent studies on fluid-structure interaction problems in the presence of free surface flow. We consider the dynamics of boats simulated as rigid bodies. Several hydrodynamic models are presented, ranging from full Reynolds averaged Navier-Stokes equations to reduced models based on potential flow theory. Copyright (C) 2007 John Wiley & Sons, Ltd.
In this paper, we focus on fluid-structure interaction (FSI) modeling of ringsail parachutes, where the geometric complexity created by the "rings" and "sails" used in the construction of the parac...
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In this paper, we focus on fluid-structure interaction (FSI) modeling of ringsail parachutes, where the geometric complexity created by the "rings" and "sails" used in the construction of the parachute canopy poses a significant computational challenge. It is expected that NASA will be using a cluster of three ringsail parachutes, referred to as the "mains", during the terminal descent of the Orion space vehicle. Our FSI modeling of ringsail parachutes is based on the stabilized space-time FSI (SSTFSI) technique and the interface projection techniques that address the computational challenges posed by the geometric complexities of the fluid-structure interface. Two of these interface projection techniques are the FSI Geometric Smoothing Technique and the Homogenized Modeling of Geometric Porosity. We describe the details of how we use these two supplementary techniques in FSI modeling of ringsail parachutes. In the simulations we report here, we consider a single main parachute, carrying one third of the total weight of the space vehicle. We present results from FSI modeling of offloading, which includes as a special case dropping the heat shield, and drifting under the influence of side winds.
The design of long-span bridges to resist wind loading often requires wind tunnel testing of sectional or full aeroelastic models. Recently, efforts have been made to realise a reliable computational alternative to th...
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The design of long-span bridges to resist wind loading often requires wind tunnel testing of sectional or full aeroelastic models. Recently, efforts have been made to realise a reliable computational alternative to these physical tests. In the current work, a novel computational scheme for fluid-structure interaction (FSI) is presented. Large eddy simulation (LES) for 3D viscous turbulent incompressible flow has been coupled to the response of prismatic line-like structures. LES is chosen because of the inherent unsteadiness in FSI problems and the capability of LES to maintain the turbulence structure in the flow, in contrast to the over-dissipativeness of the traditional Reynolds averaged Navier-Stokes equations (RANS)-based turbulence models. A Gauss-Seidel-type block-iterative algorithm is adopted to address both the field coupling and the non-linearity simultaneously. At global convergence, this gives solutions identical to those obtained using direct coupling, but with field modularity preserved, storage requirements well under control and computational effort significantly reduced. Numerical examples are presented for elastically supported rigid circular and rectangular cylinders (sectional model tests);the method is readily extendable to flexible structures (full aeroelastic models) via modal analysis. (c) 2007 Elsevier Ltd. All rights reserved.
In this article we discuss the application of a Lagrange multiplier based fictitious domain method for the simulation of the motion of two rigid flaps in an unsteady flow generated by pressure gradients. The distribut...
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In this article we discuss the application of a Lagrange multiplier based fictitious domain method for the simulation of the motion of two rigid flaps in an unsteady flow generated by pressure gradients. The distributed Lagrange multiplier technique can be an important numerical tool to design a mechanical heart valve and investigate the flow around rigid flaps without assuming the motion of the flaps in advance. Here, we derive a mathematical formulation of a fluid-structure interaction model that includes the generalized Neumann boundary conditions on the upstream and downstream boundaries along with rigid flaps rotating around the fixed points. The solution method includes the finite element approximation for space and the Marchuk-Yanenko operator splitting scheme for time discretization. This study presents the numerical results obtained for flap motion for a simple sinusoidal wave. Furthermore, these simulations are extended to apply to a more complex biological system involving the systolic phase of the pulse pressure. (c) 2007 Elsevier Ltd. All rights reserved.
fluid-structure interaction (FSI) simulations of a cerebral aneurysm with the linearly elastic and hyper-elastic wall constitutive models are carried out to investigate the influence of the wall-structure model on pat...
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fluid-structure interaction (FSI) simulations of a cerebral aneurysm with the linearly elastic and hyper-elastic wall constitutive models are carried out to investigate the influence of the wall-structure model on patient-specific FSI simulations. The maximum displacement computed with the hyper-elastic model is 36% smaller compared to the linearly elastic material model, but the displacement patterns such as the site of local maxima are not sensitive to the wall models. The blood near the apex of an aneurysm is likely to be stagnant, which causes very low wall shear stress and is a factor in rupture by degrading the aneurysmal wall. In this study, however, relatively high flow velocities due to the interaction between the blood flow and aneurysmal wall are seen to be independent of the wall model. The present results indicate that both linearly elastic and hyper-elastic models can be useful to investigate aneurysm FSI.
Electrostatic micro-devices are simple but important for MEMS applications. Precise dynamic descriptions of these devices are often hard to obtain due to the electrostatic nonlinearity and the fluid-structure interact...
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ISBN:
(纸本)9783037857397
Electrostatic micro-devices are simple but important for MEMS applications. Precise dynamic descriptions of these devices are often hard to obtain due to the electrostatic nonlinearity and the fluid-structure interactions in devices. Here we present a comprehensive electrostatic-mechanical- fluidic coupling transient analysis for the pull-in process of two ends fixed micro-plate device. The numerical results are compared with the published experiment works of other researchers available in the literature, and thus the model had been validated. After that the proper orthogonal decomposition approach is performed for the snapshot matrixes which are sampled from an ensemble of the fully finite element results. The resulted spatial distribution modes of pressure show a higher spatial frequency toward the middle of the micro-plate, which indicates that the pressures at the moving edges of the plate are not equal to ambient pressure. Due to the increasing demands for simulation accuracy, the electrostatic-mechanical interactions and the nonlinear features of viscous loss from the surrounding fluid have to be taken into account in details.
There is an increasing interest in the marine industry to use composites to improve the hydrodynamic and structural performance of naval structures. Composite materials have high strength-to-weight and stiffness-to-we...
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There is an increasing interest in the marine industry to use composites to improve the hydrodynamic and structural performance of naval structures. Composite materials have high strength-to-weight and stiffness-to-weight ratios, and the fiber orientations can be exploited to tailor the structural deformation to reduce the load and stress variations by automatically adjusting the shape of the structure. For marine propellers, the bending-twisting coupling characteristics of anisotropic composites can be exploited to passively tailor the blade rake, skew, and pitch distributions to improve propeller performance. To fully explore the advantages of composite marine propellers, a coupled boundary element (BEM) and finite element (FEM) approach is presented to study the fluid-structure interaction of flexible composite propellers in subcavitating and cavitating flows. An overview of the formulation for both the fluid and structural models is presented. Experimental validation studies are shown for two composite propellers tested at the Naval Surface Warfare Center (NSWCCD). The feasibility of passive hydroelastic tailoring of composite marine propellers is discussed. Published by Elsevier Ltd.
The patients with aortic aneurysm, especially aortic arch aneurysm, are prone to have aortic dissection. For investigation of the effect of aneurysm and wall stiffness on wall stress distribution, both the nonaneurysm...
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The patients with aortic aneurysm, especially aortic arch aneurysm, are prone to have aortic dissection. For investigation of the effect of aneurysm and wall stiffness on wall stress distribution, both the nonaneurysm arch model and the aneurysm arch model are constructed. The fluidstructureinteraction in the arch model of aorta was implemented. The results show the stresses are much higher at inflection points in aneurysm model than in nonaneurysm model. and the stresses at media in stiffened wall are higher than in unstiffened wall. The high composite stress is located at inflection points and is much higher in aneurysm model. The arch aneurysm and wall stiffening are important determinants of peak wall stress in aortic wall.
fluid-structure interaction of panel in supersonic fluid passage is studied with subcycling and spline interpolation based predict-correct scheme. The passage is formed with two parallel panels, one is rigid and the o...
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fluid-structure interaction of panel in supersonic fluid passage is studied with subcycling and spline interpolation based predict-correct scheme. The passage is formed with two parallel panels, one is rigid and the other is flexible. The interaction between fluid flows and flexible panel is numerically studied, mainly focused on the effect of dynamic pressure and distance between two parallel panels. Subcycling and spline interpolation based predict-correct scheme is utilized to combine the vibration and fluid analysis and to stabilize long-term calculations to get accurate results. It’s demonstrated that the flutter characteristic of flexible panel is more complex with the increase of dynamic pressure and the decrease of distance between two parallel panels. Via analyzing the propagation and reflection of disturbance in passage, it’s determined as a main cause of the variations.
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