Iranian Journal of Chemical Engineering (IJChE)

Abstract The plane Poiseuille flow with unequal wall temperatures of an incompressible fluid having temperature dependent viscosity in the presence of transverse magnetic field is studied. The coupled differential equations of momentum and energy are solved numerically by RKF45 (Runge-Kutta-Fehlberg fourth-fifth) method. Numerical results for the dimensionless velocity profiles, the temperature profiles and the heat transfer coefficient are presented and discussed graphically for various parameters. The study provides quantitative information of interest; in general, it is observed that the maximum velocity does not occur in the middle of the channel but moves towards the upper wall as the magnetic field increases. The temperature and heat transfer coefficient increases with the increasing value of magnetic field and EPr.

Abstract In the current study, numerical simulation of laminar flow and heat transfer of water mixture with carbon nanotubes (CNT) as nanofluids in a 90 degree curved pipe are considered. The incompressible Navier-Stokes and energy equations are solved numerically in a body fitted coordinates system using a control volume technique. An interfacial layer-based model is applied to predict the thermal conductivity of nanofluid. The axial velocity contours, secondary flow patterns and temperature fields for different values of the particles concentrations are examined in detail. Furthermore, the effects of nanoparticles concentration on the heat transfer are studied. The results indicate that due to the secondary flows induced by curvature effects, the heat transfer rate is improved, and enhanced remarkably further using nanofluids. Furthermore, the nanoparticles, especially at higher concentration levels, generate more uniform cross sectional temperature distributions.