Computational study of flow–induced oscillation of a simplified soft palate

Two-dimensional numerical simulations are employed to study fluid structure interaction soft palate in the pharynx for uniform inhalation. We take a next step towards a better biomechanical system by modeling the motion of an inextensible flexible plate. The improved structural model discretized by a low order difference method permits us to simulate the two-dimensional motion of the flexible plate. The inspiratory airflow is described by the Navier–Stokes equations for compressible flow solved by a high order difference method. The explicitly coupled fluid re interaction model is based on the Arbitrary Lagrangian–Eulerian formulation

A strongly-coupled immersed-boundary formulation for thin elastic structures

We present a strongly-coupled immersed-boundary method for flow–structure interaction problems involving thin deforming bodies. The method is stable for arbitrary choices of solid-to-fluid mass ratios and for large body motions. As with many strongly-coupled immersed-boundary methods, our method requires the solution of a nonlinear algebraic system at each time step. The system is solved through iteration, where the iterates are obtained by linearizing the system and performing a block-LU factorization. This restricts all iterations to small-dimensional subsystems that scale with the number of discretization points on the immersed surface, rather than on the entire flow domain. Moreover, the iteration procedure we propose does not involve heuristic regularization parameters, and has converged in a small number of iterations for all problems we have considered. We derive our method for general deforming surfaces, and verify the method with two-dimensional test problems of geometrically nonlinear flags undergoing large amplitude flapping behavior

Bifurcation and chaos of a flag in an inviscid flow

A two-dimensional model is developed to study the flutter instability of a flag immersed in an inviscid flow. Two dimensionless parameters governing the system are the structure-to-fluid mass ratio M⁎ and the dimensionless incoming flow velocity U⁎. A transition from a static steady state to a chaotic state is investigated at a fixed M⁎=1 with increasing U⁎. Five single-frequency periodic flapping states are identified along the route, including four symmetrical oscillation states and one asymmetrical oscillation state. For the symmetrical states, the oscillation frequency increases with the increase of U⁎, and the drag force on the flag changes linearly with the Strouhal number. Chaotic states are observed when U⁎ is relatively large. Three chaotic windows are observed along the route. In addition, the system transitions from one periodic state to another through either period-doubling bifurcations or quasi-periodic bifurcations, and it transitions from a periodic state to a chaotic state through quasi-periodic bifurcations

Immersed boundary method combined with proper generalized decomposition for simulation of a flexible filament in a viscous incompressible flow

In this paper, a combination of the Proper Generalized  Decomposition (PGD) with the Immersed Boundary method (IBM) for solving  fluid-filament interaction problem is proposed. In this combination, a  forcing term constructed by the IBM is introduced to Navier-Stokes equations  to handle the influence of the filament on the fluid flow. The PGD is  applied to solve the Poission's equation to find the fluid pressure  distribution for each time step. The numerical results are compared with  those by previous publications to illustrate the robustness and  effectiveness of the proposed method

Fixed-mesh approach for different dimensional solids in fluid flows : application to biological mechanics

S. Miyauchi, A. Ito, S. Takeuchi and T. Kajishima, "Fixed-mesh approach for different dimensional solids in fluid flows : application to biological mechanics", Journal of Mechanical Engineering and Sciences, Vol. 6, pp.818-844, UMP, 201

A strongly-coupled immersed-boundary formulation for thin elastic structures

We present a strongly-coupled immersed-boundary method for flow–structure interaction problems involving thin deforming bodies. The method is stable for arbitrary choices of solid-to-fluid mass ratios and for large body motions. As with many strongly-coupled immersed-boundary methods, our method requires the solution of a nonlinear algebraic system at each time step. The system is solved through iteration, where the iterates are obtained by linearizing the system and performing a block-LU factorization. This restricts all iterations to small-dimensional subsystems that scale with the number of discretization points on the immersed surface, rather than on the entire flow domain. Moreover, the iteration procedure we propose does not involve heuristic regularization parameters, and has converged in a small number of iterations for all problems we have considered. We derive our method for general deforming surfaces, and verify the method with two-dimensional test problems of geometrically nonlinear flags undergoing large amplitude flapping behavior