Particle‐based realistic simulation of fluid–solid interaction

In this paper a novel method for simulating incompressible viscous fluid and solid coupling is presented. In the coupling model, a rigid object is treated as a special fluid constrained to rigid body motion. To animate the coupling model, the Smoothed Particle Hydrodynamics method is used for solving the fluid motion equations. For keeping the rigidity of rigid objects, the total force and total torque exerted on solids is first worked out according to the impulse–momentum theorem, and then the movement of these rigid bodies is restricted to translations and rotations. Moreover, in order to prevent the fluids particles leaking into solids, a detection and correction procedure is presented, and the velocities of fluid particles will be tuned if the penetration is detected in this procedure. The proposed method can be implemented easily by extending the existing fluid solvers, the experimental results show that this method is capable of animating the realistic solid and fluid coupling. Copyright © 2010 John Wiley & Sons, Ltd.     

Application of the dynamic compliance method for fluid–structure interaction

This article is focused on application of the dynamic compliance method for fluid–structure interaction. The dynamic compliance method is in principle a method which provided reduction of the order in the frequency domain. This method has been implemented in MATLAB and tested on a relatively simple structure and fluid models. Results were compared with the exact solution and a good agreement was found.     

Fluid–structure interaction simulation of aortic blood flow

The numerical tools to simulate blood flow in the cardiovascular system are constantly developing due to the great clinical interest and to scientific advances in mathematical models and computational power. The present work aims to address and validate new algorithms to efficiently predict the hemodynamics in large arteries. These algorithms rely on finite elements simulation of the fluid–structure interaction between blood flow and arterial wall deformation of a healthy aorta. Different sets of boundary conditions are devised and tested. The mean velocity and pressure time evolution is plotted on different sections of the aorta and the wall shear stress distribution is computed. The results are compared with those obtained with a rigid wall simulation. Pulse wave velocity is computed and compared with the values available from the literature. The flow boundary conditions used for the outlets are obtained using the solution of a one-dimensional model. The results of the simulations are in agreement with the physiological data in terms of wall shear stress, wall displacement, pressure waveforms and velocities.     

Particle‐based simulation of bubbles in water–solid interaction

In this paper, a particle‐based multiphase method for creating realistic animations of bubbles in water–solid interaction is presented. To generate bubbles from gas dissolved in the water on the fly, we propose an approximate model for the creation of bubbles, which takes into account the influence of gas concentration in the water, the solid material, and water–solid velocity difference. As the air particle on the bubble surface is treated as a virtual nucleation site, the bubble absorbs air from surrounding water and grows. The density and pressure forces of air bubbles are computed separately using smoothed particle hydrodynamics; then, the two‐way coupling of bubbles with water and solid is solved by a new drag force, so the generated bubbles’ flow on the surface of solid and the deformation in the rising process can be simulated. Additionally, touching bubbles merge together under the cohesion forces weighted by the smoothing kernel and velocity difference. The experimental results show that this method is capable of simulating bubbles in water–solid interaction under different physical conditions. Copyright © 2012 John Wiley & Sons, Ltd.     

Solving the block–Toeplitz least‐squares problem in parallel

In this paper we present two versions of a parallel algorithm to solve the block–Toeplitz least‐squares problem on distributed‐memory architectures. We derive a parallel algorithm based on the seminormal equations arising from the triangular decomposition of the product T^TT. Our parallel algorithm exploits the displacement structure of the Toeplitz‐like matrices using the Generalized Schur Algorithm to obtain the solution in O(mn) flops instead of O(mn²) flops of the algorithms for non‐structured matrices. The strong regularity of the previous product of matrices and an appropriate computation of the hyperbolic rotations improve the stability of the algorithms. We have reduced the communication cost of previous versions, and have also reduced the memory access cost by appropriately arranging the elements of the matrices. Furthermore, the second version of the algorithm has a very low spatial cost, because it does not store the triangular factor of the decomposition. The experimental results show a good scalability of the parallel algorithm on two different clusters of personal computers. Copyright © 2005 John Wiley & Sons, Ltd.