We present a monolithic Lagrangian meshfree solution for fluid-structure interaction (FSI) problems within the Optimal Transportation Meshfree (OTM) framework. The governing equations of the fluid and structure are fo...
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We present a monolithic Lagrangian meshfree solution for fluid-structure interaction (FSI) problems within the Optimal Transportation Meshfree (OTM) framework. The governing equations of the fluid and structure are formulated in the Lagrangian configuration and solved simultaneously in a monolithic way. Mainly, the fully discretized equations are constructed by leveraging on the OTM method to address the challenges in the Lagrangian description of the fluid domain. In this approach, the fluid-structure interface becomes an internal surface of the entire field, and the continuity and force equilibrium on the interface are automatically satisfied without any extra computations. The monolithic Lagrangian solution provides enhanced stability comparing to partitioning approaches and eliminates the problem of free surface and material interface tracking. The presented method enables a Direct Numerical Simulation (DNS) of the fluid flow with the absence of the convective terms. The accuracy and robustness of the OTM FSI approach are systematically investigated by the classical Blasius solution of the boundary layer problem. Furthermore, we illustrate the range and scope of the method through two examples: the impact of a rigid body on the fluid domain in a container and the interaction between the fluid and highly flexible structures in an open channel. (C) 2018 Elsevier B.V. All rights reserved.
Body-fitted and Cartesian grid methods are two typical types of numerical approaches used for modelling fluid-structure interaction problems. Despite their extensive applications, there is a lack of comparing the perf...
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Body-fitted and Cartesian grid methods are two typical types of numerical approaches used for modelling fluid-structure interaction problems. Despite their extensive applications, there is a lack of comparing the performance of these two types of approaches. In order to do this, the present paper presents benchmark numerical solutions for two two-dimensional fluid-structure interaction problems: flow-induced vibration of a highly flexible plate in an axial flow and a pitching flexible plate. The solutions are obtained by using two partitioned fluid-structure interaction methods including the deforming-spatial-domain/stabilized space-time fluid-structure interaction solver and the immersed boundary-lattice Boltzmann method. The deforming-spatial-domain/stabilized space-time fluid-structure interaction solver employs the body-fitted-grid deforming-spatial-domain/stabilized space-time method for the fluid motions and the finite-difference method for the structure vibrations. A new mesh update strategy is developed to prevent severe mesh distortion in cases where the boundary does not oscillate periodically or needs a long time to establish a periodic motion. The immersed boundary-lattice Boltzmann method uses lattice Boltzmann method as fluid solver and the same finite-difference method as structure solver. In addition, immersed boundary method is used in the immersed boundary-lattice Boltzmann solver to handle the fluid-structure interaction coupling. Results for the characteristic force coefficients, tail position, plate deformation pattern and the vorticity fields are presented and discussed. The present results will be useful for evaluating the performance and accuracy of existing and new numerical methodologies for fluid-structure interaction.
We present a novel framework inspired by the Immersed Boundary Method for predicting the fluid-structure interaction of complex structures immersed in laminar, transitional and turbulent flows. The key elements of the...
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We present a novel framework inspired by the Immersed Boundary Method for predicting the fluid-structure interaction of complex structures immersed in laminar, transitional and turbulent flows. The key elements of the proposed fluid-structure interaction framework are 1) the solution of elastodynamics equations for the structure, 2) the use of a high-order Navier-Stokes solver for the flow, and 3) the variational transfer (L-2-projection) for coupling the solid and fluid subproblems. The dynamic behavior of a deformable structure is simulated in a finite element framework by adopting a fully implicit scheme for its temporal integration. It allows for mechanical constitutive laws including inhomogeneous and fiber-reinforced materials. The Navier-Stokes equations for the incompressible flow are discretized with high-order finite differences which allow for the direct numerical simulation of laminar, transitional and turbulent flows. The structure and the flow solvers are coupled by using an L-2-projection method for the transfer of velocities and forces between the fluid grid and the solid mesh. This strategy allows for the numerical solution of coupled large scale problems based on nonconforming structured and unstructured grids. The transfer between fluid and solid limits the convergence order of the flow solver close to the fluid-solid interface. The framework is validated with the Turek-Hron benchmark and a newly proposed benchmark modelingthe flow-induced oscillation of an inert plate. A three-dimensional simulation of an elastic beam in transitional flow is provided to show the solver's capability of coping with anisotropic elastic structures immersed in complex fluid flow. (C) 2019 Elsevier Inc. All rights reserved.
This study focuses on finding high-performance numerical solutions to fluid-structure coupling problems encountered in biomechanical engineering. A numerical framework for simulating fluid-structure interaction (FSI) ...
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This study focuses on finding high-performance numerical solutions to fluid-structure coupling problems encountered in biomechanical engineering. A numerical framework for simulating fluid-structure interaction (FSI) is proposed by strongly coupling the finite element and lattice Boltzmann methods. The lattice Boltzmann method is efficient for solving weakly compressible fluid flows. The explicit finite element method (FEM) is used to solve solid structure deformation. A partitioned iterative solution is adopted to couple these two methods together. A fixed point iteration method is used with the Aitken dynamic relaxation algorithm to improve numerical stability. A multi-direct forcing immersed boundary method with a sub-iteration scheme is adopted to represent the interaction between fluid and structure. Validation of the proposed coupling method was conducted on a vortex induced vibration problem. The numerical results are in good agreement with the reference results (Li and Favier, 2017). The proposed method does not have to solve large systems of linear equations, so it is suited to parallel computation. Therefore, we then present a parallel implementation of our method on a graphics processing unit, which increases the computation speed more than 18-fold. Our developed FSI solver is very efficient, which makes it possible to provide more accurate results with finer meshes. Finally, our method is applied to the simulation of complicated motions of a bileaflet heart valve caused by blood flow. (C) 2020 Elsevier B.V. All rights reserved.
The present paper investigates the interaction between a turbulent fluid flow and a flexible membrane structure. Such flexible structures are of increasing interest for modern engineering applications due to their ada...
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The present paper investigates the interaction between a turbulent fluid flow and a flexible membrane structure. Such flexible structures are of increasing interest for modern engineering applications due to their adaptable utilization. Highly flexible membranes under turbulent flow conditions still bare fundamental challenges such as the structural response to fluid loads leading to the motivation of the present study. It investigates the fluid-structure interaction of a flexible membranous structure in the shape of a hemisphere. The air-inflated structure is placed in the test section of a wind tunnel and is exposed to a turbulent boundary layer flow. The properties of the turbulent boundary layer are clearly defined so that the test case is reproducible by numerical simulations. Three Reynolds numbers (50,000, 75,000 and 100,000) are chosen to examine the interaction between the turbulent flow and the pressurized membrane. Special emphasis is put on the instantaneous effects. Furthermore, the flow field around an equally sized rigid hemisphere is measured under identical conditions serving as a reference for the flexible case. The experiments are conducted by combining particle-image-velocimetry for the flow field and high-speed digital-image correlation measurements for the deformation of the oscillating membrane. Furthermore, a constant-temperature anemometer is used for evaluating the velocity spectra at locations close to the wall to connect the independently performed fluid and structure measurements. A thorough analysis of the comprehensive data sets for the fluid flow and the displacements of the structure leads to the characterization of the behavior of the flexible structure under changing flow conditions. (C) 2018 Elsevier Ltd. All rights reserved.
Current assessment and management of ascending thoracic aortic aneurysm (ATAA) rely heavily on the diameter of the ATAA and blood pressure rather than biomechanical and hemodynamic parameters such as arterial wall def...
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Current assessment and management of ascending thoracic aortic aneurysm (ATAA) rely heavily on the diameter of the ATAA and blood pressure rather than biomechanical and hemodynamic parameters such as arterial wall deformation or wall shear stress. The objective of the current study was to develop an accurate computational method for modeling the mechanical responses of the ATAA to provide additional information in patient evaluations. Fully coupled fluidstructureinteraction simulations were conducted using data from cases with ATAA with measured geometrical parameters in order to evaluate and analyze the change in biomechanical responses under normotensive and hypertensive conditions. Anisotropic hyperelastic material property estimates were applied to the ATAA data which represented three different geometrical configurations of ATAAs. The resulting analysis showed significant variations in maximum wall shear stress despite minimal differences in flow velocity between two blood pressure conditions. Additionally, the three different ATAA conditions identified different aortic expansions that were not uniform under pulsatile pressure. The elevated wall stress with hypertension was also geometry-dependent. The developed models suggest that ATTA cases have unique characteristic in biomechanical and hemodynamic evaluations that can be useful in risk management.
作者:
Malve, M.Bergstrom, D. J.Chen, X. B.Univ Zaragoza
Aragon Inst Engn Res C Maria de Luna S-N E-50018 Zaragoza Spain CIBER BBN
Ctr Invest Red Bioingn Biomat & Nanomed C Poeta Mariano Esquillor S-N E-50018 Zaragoza Spain Univ Publ Navarra
Dept Ingn Edificio PinosCampus Arrosadia S-N E-31006 Pamplona Spain Univ Saskatchewan
Coll Engn Dept Mech Engn Engn Bldg 57Campus Dr Saskatoon SK S7N 5A9 Canada Univ Saskatchewan
Coll Engn Div Biomed Engn Engn Bldg 57Campus Dr Saskatoon SK S7N 5A9 Canada
Tissue engineering scaffolds combined with bioreactors are used to cultivate cells with the aim of reproducing tissues and organs. The cultivating process is critical due to the delicate in-vitro environment in which ...
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Tissue engineering scaffolds combined with bioreactors are used to cultivate cells with the aim of reproducing tissues and organs. The cultivating process is critical due to the delicate in-vitro environment in which the cells should reproduce. The distribution of nutrients within the engineered construct depend on the scaffold morphology and the analysis of the fluid flow and transport phenomena under mechanical loading when the scaffold is coupled with a bioreactor is crucial for this scope. Unfortunately, due to the complicated microstructure of the scaffold, it is not possible to perform this analysis with experiments and numerical simulation can help in this sense. In this study we have computed the fluid flow and the mass transport of a parametrized scaffold in perfusion bioreactors analyzing the influence of the microstructure of the scaffold using the fluid-structure interaction approach. The latter allows considering the porous construct as compliant yet determining important structural parameters such as stresses and strains that could be sensed by the cells. The presented model considered flow perfusion that provided nutrients and mechanical compression. In particular, we have studied the effect of controllable parameters such as the diameter of the scaffold strand and the porosity on the mechanical stresses and strains, shear stress and mass transport. The results of this work will help to shed light on the necessary microenvironment surrounding the cultivated cells improving culturing scaffold fabrication.
A novel adaptive time stepping scheme for fluid-structure interaction (FSI) problems is proposed that allows for controlling the accuracy of the time-discrete solution. Furthermore, it eases practical computations by ...
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A novel adaptive time stepping scheme for fluid-structure interaction (FSI) problems is proposed that allows for controlling the accuracy of the time-discrete solution. Furthermore, it eases practical computations by providing an efficient and very robust time step size selection. This has proven to be very useful, especially when addressing new physical problems, where no educated guess for an appropriate time step size is available. The fluid and the structure field, but also the fluid-structure interface are taken into account for the purpose of a posteriori error estimation, rendering it easy to implement and only adding negligible additional cost. The adaptive time stepping scheme is incorporated into a monolithic solution framework, but can straightforwardly be applied to partitioned solvers as well. The basic idea can be extended to the coupling of an arbitrary number of physical models. Accuracy and efficiency of the proposed method are studied in a variety of numerical examples ranging from academic benchmark tests to complex biomedical applications like the pulsatile blood flow through an abdominal aortic aneurysm. The demonstrated accuracy of the time-discrete solution in combination with reduced computational cost make this algorithm very appealing in all kinds of FSI applications.
fluidstructure response of vertical axis tidal turbine blades using NACA 0012 and periodic inflow equivalence model are predicted in this work. The response is investigated numerically by developing a two-dimensional...
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fluidstructure response of vertical axis tidal turbine blades using NACA 0012 and periodic inflow equivalence model are predicted in this work. The response is investigated numerically by developing a two-dimensional computational fluid dynamics model at high Reynolds number (3.07x10(6)). The Periodic Inflow Equivalence Model is conducted by modeling the rotation of the turbine as a time-dependent incoming fluid velocity magnitude and angle of attack current entering the two-dimensional computational fluid dynamics domain. The blade response is modeled by a vibrational system with spring damper components which are attached at the blade fluid dynamic center point. The aim of this study is to predict a resonant condition or a lock-in frequency induced by wake generation at a vertical axis turbine blade during the turbine operation. The model is generated using a dynamic mesh construction in OpenFOAM 2.2, and the mesh is refined using snappyHexMesh utility. The mesh has seven added boundary layers around the blade surface and simulated using k- shear stress transport turbulence model. Drag, lift, and moment force coefficient are observed during 12s, which is equal to 3.3 revolutions, and extracted using fast Fourier transform method to obtain its predominant frequency. The predominant frequency determines the dynamic condition of the blade and is used for predicting a resonance based on the turbine's natural frequency. The result shows that the vertical axis tidal turbine which is manufactured from a composite material with pitch stiffness of 200(Nm)/rad, heave stiffness of 1000N/s, and operates at tidal velocity of 0.656m/s is found to experience a resonance or lock-in phenomena induced by wake generation in the pitch mode response.
In the present work, we perform numerical simulations of the fluid flow in type B aortic dissection (AD), accounting for the flexibility of the intimal flap. The interaction of the flow with the intimal flap is modele...
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In the present work, we perform numerical simulations of the fluid flow in type B aortic dissection (AD), accounting for the flexibility of the intimal flap. The interaction of the flow with the intimal flap is modeled using a monolithic arbitrary Lagrangian/Eulerian fluid-structure interaction model. The model relies on choosing velocity as the kinematic variable in both domains (fluid and solid) facilitating the coupling. The fluid flow velocity and pressure evolution at different locations is studied and compared against the experimental evidence and the formerly published numerical simulation results. Several tear configurations are analyzed. Details of the fluid flow in the vicinity of the tears are highlighted. Influence of the tear size upon the fluid flow and the flap deformation is discussed.
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