화학공학소재연구정보센터
Chemical Engineering Research & Design, Vol.84, No.A12, 1180-1193, 2006
Sedimentation in emulsions of mono-size droplets at moderate Reynolds numbers
The steady incompressible flow of a Newtonian fluid through an ensemble of Newtonian fluid spheres has been numerically investigated using a finite difference method based SMAC algorithm. For both, dispersed and continuous phases, the convective terms have been discretized using the QUICK scheme, and diffussive terms with the second-order central differencing scheme. A simple concentric sphere cell model has been employed to account for inter-particle hydrodynamic interactions. Extensive numerical results on pressure drag (C-dp), friction drag (C-df) and total drag (C-D) coefficients have been presented as functions of the Reynolds number (Re-o) for the continuous phase, the volume fraction of the dispersed phase (epsilon), and the ratio of internal to external fluid viscosity (k) over the ranges of conditions: 1 <= Re-o <= 500, 0.2 <= epsilon <= 0.6 and 0.1 <= k <= 50. Based on the numerical values of the total drag coefficients obtained in this work, a simple correlation has been proposed which can be used to predict the rate of sedimentation in liquid-liquid systems.