Fluid-structure interaction

Purely electrical models of the heart are only a start. Combined electromechanical finite-element models of the heart take into account the close relationship that exists between the electrical and mechanical properties of individual heart cells. The mechanical operation of the heart is also influenced by the fluid-structure interactions between the blood and the blood vessels, heart walls, and valves. All of these interactions would need to be included in a complete description of heart contraction. 

Analysis of fluid structure interaction within a pipe constriction. 

This problem falls into a category of strongly coupled fluid-structure interaction (FSI) problems due to comparable stiffnesses of the container and its liquid content. Hence, accurate prediction of containers behaviour requires a liquid-container interaction model. Here, a two-system FSI model based on the Finite Volume Method is employed, and a good agreement is found between measured and predicted pressure and strain histories. 

To obtain fracture properties of HDPE conventional essential work of ifacture tests are performed. Two grades of blow-moulded HDPE are tested at different test speeds. The main aim of these tests is to estimate traction-separation (cohesive zone) properties of the materials. In future work, these will be combined with the fluid-structure interaction model to provide a powerful tool for predicting the complex behaviour and potential failure of fluid-filled containers imder drop impact. 

This paper presents the combined experimental/numerical investigation of the behaviour of fluid-filled plastic containers subjected to drop impact. Drop Impact experiments were conducted on original and modified bottles. During the test, strain and pressure histories were recorded at various positions. Tests were simulated numerically using the two-system FSI model. Both solid and fluid domains remain fixed during the calculations, i.e. a small-strain analysis was performed for the solid while an Eulerian fi-ame of reference was used for the fluid. This procedure was found to be simple, stable and efficient. Numerical results agreed well with experimental data, demonstrating the capability of the code to cope with this complex fluid-structure interaction problem. 

A. Ivankovic, A. Karac, E. Dendrinos, K. Parker, Towards Early Diagnosis of Atherosclerosis The Finite Volume methods for Fluid-Structure Interaction, Biorheology 39 (2002), 401-407. 

Donea J, Giuliani S, Halleux JP (1982) An Arbitrary Lagrangian-Eulerian Finite Element Method for Transient Dynamic Fluid-Structure Interactions. Computer Methods in Applied Mechanics and Engineering 33 689-723... 

Valette, R., Vergnes, B., Coupez, T. Multiscale simulation of mixing processes using 3d-parallel, fluid-structure interaction techniques. International Journal of Material Forming (Proc. Symposium MS16 ESAFORM-ECCOMAS Workshop, Paris, France) (2008)... 

Development of an Optimal Fluid Structure Interaction System That Promotes Cube Alignment and Docking... 

Meshless methods have high potentials to be employed in simulation of fluid-structure interactions. Complex geometries and interaction history can be defined using meshless methods requiring far less efforts. 

Acoustic waves can potentially damage biological samples (e.g., cause cell lysis). Due to this reason, careful control of the SAW frequency and device optimization are necessary. Understanding the complicated mechanisms governing the fluid-structure interactions will help in the optimization of ultrasonic pumps dealing with biological samples. 

Optimization of operational conditions focusing on dynamic fluid-structure interactions ... 

Under the hypothesis of rigid tank, the impulsive and convective part of hydrodynamic pressure can be easily evaluated. On the contrary, the p>art, which depends on the deformability of the tank wall, can be determined solving a fluid-structure interaction problem, whose solution depends on the geometrical and mechanical characteristics of the tank radius R, liquid level H, thickness s, liquid density p and elastic modulus of steel E. The problem can be uncoupled in infinite vibration modes, but only few of them have a significant mass. Thus, the impulsive mass is distributed among the first vibration modes of the wall. 

For the convective component of motion, although the value of the fundamental frequency was very close to the theoretical value (0.4 Hz), the comparison between numerical and experimental results proved unsatisfactory, because of non-zero initial conditions due to a low damping of the liquid motion. The numerical-experimental agreement is improved in the cases C and D. In fact, in these cases the fluid-structure interaction become less important and the high damping of the liquid motion arrests oscillations more rapidly, allowing zero initial conditions. 

Pulsatile flow in an elastic vessel is very complex, since the tube is able to undergo local deformations in both longitudinal and circumferential directions. The unsteady component of the pulsatile flow is assumed to be induced by propagation of small waves in a pressurized elastic tube. The mathematical approach is based on the classical model for the fluid-structure interaction problem, which describes the dynamic equilibrium between the fluid and the tube thin wall (Womersley, 1955b Atabek and Lew, 1966). The dynamic equilibrium is expressed by the hydrodynamic equations (Navier-Stokes) for the incompressible fluid flow and the equations of motion for the wall of an elastic tube, which are coupled together by the boundary conditions at the fluid-wall interface. The motion of the liquid is described in a fixed laboratory coordinate system (f , 6, f), and the dynamic... 

Computational fluid dynamics models were developed over the years that include the effects of leaflet motion and its interaction with the flowing blood (Bellhouse et al., 1973 Mazumdar, 1992). Several finite-element structural models for heart valves were also developed in which issues such as material and geometric nonlinearities, leaflet structural dynamics, stent deformation, and leaflet coaptation for closed valve configurations were effectively dealt with (Bluestein and Einav, 1993 1994). More recently, fluid-structure interaction models, based on the immersed boundary technique. 

Seismic response of the main reactor vessel and internal. 3D effects are being studied taking into account fluid-structure interactions. Comparison with 2D calculations are in progress. 

Sodium release to RGB under CD A has been estimated at about 1.5 t, based on the approach followed for FFTF reactor. The important input to this analysis are the transient and quasi-static pressure of the sodium after slug impact beneath the top shield and the fraction of the sodium mass in the reactor assembly which has potential to get ejected. These parameters are obtained from the detailed fast transient fluid-structure interaction analysis using an in-house computer code called FUSTIN. A preliminary estimate is also made on the transient pressure and temperature rise in the RGB for the 1.5 t of sodium release and the values are 30 kPa and 80 K respectively. 

For high-fidelity fluid-structure interaction simulations different tools are necessary to allow the highest possible accuracy. In this context the data transfer between the... 

Afterwards an update to the mesh deformation module is presented, which enables to represent the exact deflections for every CFD surface grid node, which are delivered by the coupling matrix. Performance limitations do not allow to use all points as input for the basic radial-basis-function based mesh deformation method. Then the FSI-loop to compute the static elastic equilibrium is described and the application to an industrial model is presented. Finally, a strategy how to couple and deflect control smfaces is shown. Therefore, a possible gapless representation by means of different coupling domains and a chimera-mesh representation is shown. This section describes the bricks, which are combined to a fluid-structure interaction loop. Most of the tools are part of the FlowSimulator software environment (Fig. 20.11). 

Fig. 20.11 Static fluid-structure interaction loop with additional trim loop...

Chelghoum,A., Dowling, P.J., An Updated Lagrangian Finite element Approach to Non-linear Fluid Structure Interaction Problems . 

Sonntag SJ, Kanfmann TA, Biisen MR, Laumen M, Linde T, Schmitz-Rode T, et al. Simulation of a pulsatile total artificial heart development of a partitioned fluid structure interaction model. J Fluids Struct 2013 38 187-204. 

J. Chaplin, Vortex- and wake-induced vibrations of deep water risers, Fourth Int. Conf. Fluid Structure Interaction, Ashurst, Southampton, UK (2007). 

M. H. Kim and W. C. Koo, 2D fuUy nonhnear numerical wave tanks, Numerical Modeling in Fluid-Structure Interaction, ed. S. K. Chakrabarti (WIT Press, Great Britain, 2005), Chap. 2. 

In recent years, the SPH methods in particular have gone through major improvements and their application was expanded into a wider range of engineering problems. These include both more advanced physical models and more advanced engineering processes. For example, SPH was successfully used to simulate non-Newtonian fluid flows and viscoelastic materials. It has been also used for the analysis of fluid-structure interaction problems, fluid flow in porous media and fractures, heat transfer and reacting flow problems. 

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