Authors: S. Chen, N. Phan-Thien, X.J. Fan and B.C. Khoo
Affilation: National University of Singapore, Singapore
Pages: 246 - 249
Keywords: droplets, emulsion, suspension, dissipative paticle dynamics
In the present study, the dynamics of polymer drops in micro channel under both steady state and transient shear flow conditions are investigated using Dissipative Particle Dynamics method. The polymer drop is made from finitely extensible non-linear elastic (FENE) bead spring chains with each chain consisting of 16 beads. The rheological behaviors of shear thinning and normal stress difference effects are observed. For the polymer drop in steady state shear field, the relationship between the deformation parameter (D) and Capillary number (Ca) could be divided into linear regime and nonlinear regime, which is in qualitatively agreement with the experimental results of Guido. As shear rates increased further, the polymer drop begins to elongate, the drop will eventually break up, and in the mean time, possible coalescence will occurs for two neighboring drops.The dynamical equilibrium between breakup and coalescence will result in a steady-state average droplet-size distribution. For the elongated and oriented polymer drop undergoing shear reversal it will retract affinely towards a roughly spherical shape firstly.