Small and micro unmanned aircraft are the focus of scientific interest due to their wide range of *** often operate in a highly unstable flight environment where the application of new morphing wing technologies offer...
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Small and micro unmanned aircraft are the focus of scientific interest due to their wide range of *** often operate in a highly unstable flight environment where the application of new morphing wing technologies offers the opportunity to improve flight *** investigated concept comprises port and starboard adjustable wings,and an adaptive elastoflexible membrane serves as the lifting *** focus is on the benefits of the deforming membrane during the impact of a one-minus-cosine type *** a low Reynolds number of Re=264000,the morphing wing model is investigated numerically by unsteady fluid-structure interaction ***,the numerical results are validated by experimental data from force and moment,flow field,and deformation ***,with the rigid wing as the baseline,the flexible case is investigated,focusing on the advantages of the elastic *** all configurations studied,the maximum amplitude of the lift coefficient under gust load shows good agreement between the experimental and numerical *** the decay of the gust,they differ more the higher the aspect ratio of the *** considering the flow field,the main differences are due to the separation behavior on the upper side of the *** flow reattaches earlier in the experiments than in the simulations,which explains the higher lift values observed in the *** at one intermediate configuration does the lift amplitude of the rigid configuration exceeds that of the flexible by about 12%,with the elastic membrane resulting in a smaller and more uniform peak load,which is also evident in the wing loading and hence in the root bending moment.
An experimental setup was developed for channel driven cavity flow in order to study the fluid- structureinteraction and provide benchmark data for validation of numerical fluid-structure interaction models. The chan...
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An experimental setup was developed for channel driven cavity flow in order to study the fluid- structureinteraction and provide benchmark data for validation of numerical fluid-structure interaction models. The channel driven cavity flow is a modification from lid-driven cavity flow. To examine the fluid-structure interaction, the bottom side of the cavity is a deformable flat plate. All other boundaries are rigid. The fluid-structure interaction inside the cavity is driven by flow through a thin channel topside of the cavity. Water is used as the fluid. fluid-structure interaction for different deformable plates during constant flow is quantified using a variety of strain and displacement measurement techniques. To establish suitable boundary conditions for numerical analysis of the experiment, the inlet velocity of the channel driven cavity flow is known. Outlet pressure is constant atmospheric. Numerical results are obtained using ANSYS's CFX and structure analysis.
A three-dimensional(3D) embedded Eulerian-Lagrangian method is proposed to simulate the 3D fluid-structure interaction(FSI) problems subjected to explosion and impact loading. This method achieves a high-quality calcu...
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A three-dimensional(3D) embedded Eulerian-Lagrangian method is proposed to simulate the 3D fluid-structure interaction(FSI) problems subjected to explosion and impact loading. This method achieves a high-quality calculation of fluid and structure deformation by adding Lagrangian particles to Eulerian grids. The overall computational domain is solved by the Eulerian method, and the Lagrangian particles with specified volume and influence domains are used to track structural deformations. The bidirectional mapping of physical quantities is achieved using the weighted average of the influence domain, which are based on the topological relationship between Eulerian grids and Lagrangian particles. Then, the data dependence solution and parallel algorithm realization are presented for the large-scale numerical calculations of explosion and impact problems. Additionally, the corresponding parallel program is developed based on the message passing interface(MPI) standard, and the parallel efficiency of parallel hydrocode are tested. The numerical results of typical explosion and impact problems are compared with corresponding experimental data to verify the effectiveness of the method. These comparisons show that the embedded EulerianLagrangian method successfully combine the advantages of both the Eulerian and Lagrangian methods to efficiently calculate the processes of large deformation and dynamic damage to the materials. The results presented in this work provide a useful reference point for further research on explosion and impact problems.
Heat transfer enhancement is achieved by flow-induced vibration in elastic tube bundles heat exchangers. For a further understanding of heat transfer enhancement mechanism and tube structure optimization, it is of imp...
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Heat transfer enhancement is achieved by flow-induced vibration in elastic tube bundles heat exchangers. For a further understanding of heat transfer enhancement mechanism and tube structure optimization, it is of importance to study the vibration characteristics of fluid-structure interaction of tube bundles. The finite element method is applied in the study of fluid-structure interaction of a new type elastic heat transfer element, i.e., the dimensional conical spiral tube bundle. The vibration equation and element matrix for the tube are set up by the regulation of different helical angles and coordinate transformation, together with the simplification of the joint body of the two pipes. The vibration characteristics of conical spiral tube bundle are analyzed at different velocities of the tube-side flow, and the critical velocity of vibration buckling is obtained. The results show that the natural frequency of the tube bundle decreases as the flow speed increases, especially for the first order frequency, and the critical velocity of vibration buckling is between 1.2665 m/s-1.2669 m/s. The vibration mode of conical spiral tube bundle is mainly z-axial, which is feasible to be induced and controlled.
The effects of ground motion spatial variability(GMSV)or fluid-structure interaction(FSI)on the seismic responses of deep-water bridges have been extensively ***,there are few studies on the seismic performance of bri...
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The effects of ground motion spatial variability(GMSV)or fluid-structure interaction(FSI)on the seismic responses of deep-water bridges have been extensively ***,there are few studies on the seismic performance of bridges considering GMSV and FSI effects *** this study,the original multiple-support response spectrum(MSRS)method is extended to consider FSI effect for seismic analysis of deep-water *** solution of hydrodynamic pressure on a pier is obtained using the radiation wave theory,and the FSI-MSRS formulation is derived according to the random vibration *** influence of FSI effect on the related coefficients is analyzed.A five-span steel-concrete continuous beam bridge is adopted to conduct the numerical *** load conditions are designed to investigate the variation of the bridge responses when considering the GMSV and FSI *** results indicate that the incoherence effect and wave passage effect decrease the bridge responses with a maximum percentage of 86%,while the FSI effect increases the responses with a maximum percentage of 26%.The GMSV and FSI effects should be included in the seismic design of deep-water bridges.
A Continuum Sensitivity Equation (CSE) method was developed in local derivative form for fluid-structure shape design problems. The boundary velocity method was used to derive the continuum sensitivity equations and s...
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A Continuum Sensitivity Equation (CSE) method was developed in local derivative form for fluid-structure shape design problems. The boundary velocity method was used to derive the continuum sensitivity equations and sensitivity boundary conditions in local derivative form for a built-up joined beam structure under transient aerodynamic loads. For nonlinear problems, when the Newton-Raphson method is used, the tangent stiffness matrix yields the desired sensitivity coefficient matrix for solving the linear sensitivity equations in the Galerkin finite element formulation. For built-up structures with strain discontinuity, the local sensitivity variables are not continuous at the joints, requiring special treatment to assemble the elemental local sensitivities and the generalized force vector. The coupled fluid-structure physics and continuum sensitivity equations for gust response of a nonlinear joined beam with an airfoil model were posed and solved. The results were compared to the results obtained by finite difference (FD) method. (C) 2013 Elsevier Ltd. All rights reserved.
We propose a monolithic fluid-structure interaction (FSI) method that uses the cell-centered finite volume formulation in the Eulerian description, Lagrangian marker particles allocated in the solid region, and the in...
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We propose a monolithic fluid-structure interaction (FSI) method that uses the cell-centered finite volume formulation in the Eulerian description, Lagrangian marker particles allocated in the solid region, and the incompressible mixture formulation. In the proposed method, we compute all the basic equations and spatial derivatives, except the solid constitutive equations, on an Eulerian mesh to avoid neighboring particle search. Although full Eulerian methods that use a Cartesian mesh are attractive for FSI problems that require large-scale computing and include complex geometries and the large deformation of the solid, they cannot avoid the numerical dissipation of the interfaces or internal variables of the solid caused by their advection. This computational problem has been a barrier to the industrial application of full Eulerian mesh methods. In the numerical examples, we confirmed that the proposed method retains sharp interfaces, such as the corners of a square solid, and yields more accurate numerical results for the deformation, energy, and incompressibility of a solid in fluid than our conventional Eulerian FSI method.
The present paper provides an analysis of the force model effect on the regularization procedure based on the Hermite expansion in regularized lattice Boltzmann method (RLBM). It is shown that, when using the 2nd-orde...
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The present paper provides an analysis of the force model effect on the regularization procedure based on the Hermite expansion in regularized lattice Boltzmann method (RLBM). It is shown that, when using the 2nd-order accurate in time semi-implicit force model of Guo et al. [15] in RLBM, the reconstruction of the non-equilibrium part of the distribution function has to start from the 1st-order Hermite polynomial, because the new distribution function (after a change of variables) contains the body force effect. Based on this Hermite regularization, an immersed boundary-regularized lattice Boltzmann (IB-RLB) coupling method is proposed for simulating transient fluid-structure interactions (FSI) with rigid and deformable solid objects. The fluid and solid solvers are coupled in a non-staggered way so that the stability and accuracy are well preserved. The proposed IB-RLB coupling method is then validated with several numerical test-cases, such as impulsively started plate, vortex-induced vibrations and 3D flapping flag, for which good agreements are found with the references. (C) 2019 Elsevier Ltd. All rights reserved.
A direct numerical modeling method for parachute is proposed firstly, and a model for the star-shaped folded parachute with detailed structures is established. The simplified arbitrary Lagrangian-Eulerian fluid struct...
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A direct numerical modeling method for parachute is proposed firstly, and a model for the star-shaped folded parachute with detailed structures is established. The simplified arbitrary Lagrangian-Eulerian fluidstructureinteraction （SALE/FSI） method is used to simulate the infla- tion process of a folded parachute, and the flow field calculation is mainly based on operator split- ting technique. By using this method, the dynamic variations of related parameters such as flow field and structure are obtained, and the load jump appearing at the end of initial inflation stage is cap- tured. Numerical results including opening load, drag characteristics, swinging angle, etc. are well consistent with wind tunnel tests. In addition, this coupled method can get more space-time detailed information such as geometry shape, structure, motion, and flow field. Compared with previous inflation time method, this method is a completely theoretical analysis approach without relying on empirical coefficients, which can provide a reference for material selection, performance optimi- zation during parachute design.
In this paper, deck models of a cable stayed bridge are generated in ABAQUS-finite element program once using only CFD model （one-way fluid-structure interaction） and another by using both the CFD model and the CSD ...
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In this paper, deck models of a cable stayed bridge are generated in ABAQUS-finite element program once using only CFD model （one-way fluid-structure interaction） and another by using both the CFD model and the CSD model together （two-way fluid-structure interaction） in a co-simulation. Shedding frequencies for the associated wind velocities in the lock-in region are calculated in both approaches. The results are validated with Simiu and Scanlan results. The lift and drag coefficients are determined for the two approaches and the latter results are validated with the flat plate theory results by Munson and coauthors. A decrease in the critical wind velocity and the shedding frequencies considering two-way approach was determined compared to those obtained in the one-way approach. The results of the lift and drag forces in the two-way approach showed appreciable decrease in their values. It was concluded that the two-way approach predicts earlier vortex induced vibration for lower critical wind velocities and lock-in phenomena will appear at lower natural frequencies of the long span bridges. This helps the designers to efficiently plan and consider for the design and safety of the long span bridge against this type of vibration.
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