Physica A 362 (2006) 84–92 Dynamic simulation of multi-component viscoelastic fluids using the lattice Boltzmann method J. Onishi à , Y. Chen, H. Ohashi Department of Quantum Engineering and Systems Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan Available online 7 October 2005 Abstract We develop a discrete model for multi-component viscoelastic fluids based on the lattice Boltzmann method. The model newly introduces the kinetics of polymers so that viscoelasticity is included. We perform three-dimensional simulations of a Newtonian drop in shear flow of a viscoelastic fluid in order to investigate the validity of the current model. In the investigation, effects of viscoelasticity on deformation and orientation of drops are evaluated. The simulation results are compared with experimental measurements quantitatively, and they show good agreement with each other. r 2005 Elsevier B.V. All rights reserved. Keywords: Lattice Boltzmann method; Multi-component fluids; Viscoelasticity 1. Introduction The lattice Boltzmann method [1] (LBM) is a relatively new method for computational fluid dynamics (CFD). The main feature which distinguish LBM from the conventional CFD method is that LBM is based on kinetic theory. The kinetic nature of LBM is advantageous for modeling complex phenomena observed in real fluid systems, for example, complex phase behaviors of multi-component fluids such as emulsions, polymer blends, foams and so on. Indeed, using LBM models [2] they successfully simulated phase separation of immiscible liquids [3,4], and drop breakup [5], both of which involve complex interaction between phase structures and fluid flows. However, most of the previous studies assumed fluid components as Newtonian fluids. In terms of simulating phase dynamics of polymer blends, which are a typical example involving viscoelastic fluids, the effects of non-Newtonian properties should be considered. In this paper, we propose a novel model for simulating multi-component fluids, of which one or more components are non-Newtonian viscoelastic fluids, and we investigate the validity of the model by numerical simulations of a drop in shear flow of viscoelastic matrix fluid. For this purpose, we consider three levels of physics. The first is the kinetics of polymers which is the origin of viscoelasticity, the second is the hydrodynamics of the fluid with viscoelasticity, and the final is the phase dynamics in multi-component fluids. All of them are included in a single framework. Thus, our framework can ARTICLE IN PRESS www.elsevier.com/locate/physa 0378-4371/$ - see front matter r 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.physa.2005.09.022 à Corresponding author. E-mail address: onishi@crimson.q.t.u-tokyo.ac.jp (J. Onishi).