Optimizing lattice Boltzmann simulations for unsteady flows

We present detailed analysis of a lattice Boltzmann approach to model time-dependent Newtonian flows. The aim of this study is to find optimized simulation parameters for a desired accuracy with minimal computational time. Simulation parameters for fixed Reynolds and Womersley numbers are studied. We investigate influences from the Mach number and different boundary conditions on the accuracy and performance of the method and suggest ways to enhance the convergence behavior

Optimizing lattice Boltzmann simulations for unsteady flows

We present detailed analysis of a lattice Boltzmann approach to model time-dependent Newtonian flows. The aim of this study is to find optimized simulation parameters for a desired accuracy with minimal computational time. Simulation parameters for fixed Reynolds and Womersley numbers are studied. We investigate influences from the Mach number and different boundary conditions on the accuracy and performance of the method and suggest ways to enhance the convergence behavior

ACCELERATED LATTICE BGK METHOD FOR UNSTEADY SIMULATIONS THROUGH MACH NUMBER ANNEALING

We present an adaptation of the lattice BGK method for fast convergence of simulations of laminar time-dependent flows. The technique is an extension to the recent accelerated procedures for steady flow computations. Being based on Mach number annealing, the present technique substantially improves the accuracy and computational efficiency of the standard lattice BGK method for such unsteady flows

Leukocytes dynamics in microcirculation under shear-thinning blood flow

© 2009 Elsevier Ltd. All rights reserved.We present detailed simulation results of localised hemodynamics for a cluster of rolling leukocytes under shear-thinning blood flow using a lattice Boltzmann model. Leukocytes were modelled as hard spheres moving through a venule of rigid walls. The used hemorheological parameters were obtained from in vivo measurements in blood samples of Wistar rats. Velocities, shear stresses and torques were computed and visualised for each individual cell, for the cluster and for the fluid. We have found that the flow is mainly three-dimensional due to the swirling and the asymmetry of the formed vortices during the recruitment process. The shear stress is maximum on a cap covering the cell and a cone with its base on the endothelial wall at the contact region. The leukocyte is recruited to the wall with the aid of trapping vortices and four stagnant regions surrounding the cell in addition to lateral motion towards the wall. We suggest that these phenomena are highly dependent on the angular velocity of the leukocyte and on the attractive force between the leukocyte and the endothelial wall. For a moving cluster of recruited leukocytes, velocities and shear stresses as well as torques are computed. It was found that the shear stress at the endothelium gets higher as the cluster moves in the main stream enabling early initialisation of the rolling process.This work has been partially supported by the grant SFRH/BPD/20823/2004 of Fundação para a Ciência e a Tecnologia (A. Artoli) and by the project PTDC/MAT/68166/2006. FCT funds from the Centre for Mathematics and its Applications–CEMAT and the Molecular Medicine Institute–Microvascular Biology and Inflammation Unit are highly appreciated.info:eu-repo/semantics/publishedVersio