TY - JOUR
TI - Numerical study of mixed convection heat transfer in lid-driven cavity utilizing nanofluid: Effect of type and model of nanofluid
AU - Pourmahmoud Nader
AU - Ghafouri Ashkan
AU - Mirzaee Iraj
JN - Thermal Science
PY - 2015
VL - 19
IS - 5
SP - 1575
EP - 1590
PT - Article
AB - Numerical investigation of the laminar mixed convection in two-dimensional  lid driven cavity filled with water-Al2O3, water-Cu or water-TiO2 nanofluids  is done in this work. In the present study, the top and bottom horizontal  walls are thermally insulated while the vertical walls are kept at constant  but different temperatures. The governing equations are given in term of the  stream function-vorticity formulation in the non-dimensionalized form and  then solved numerically by second-order central difference scheme. The  thermal conductivity and effective viscosity of nanofluid have been  calculated by Maxwell-Garnett and Brinkman models, respectively. An excellent  agreement between the current work and previously published data on the basis  of special cases are found. The governing parameters are Rayleigh number 103  ≤ Ra ≤ 106 and solid concentration 0 ≤ φ ≤0.2 at constant Reynolds and Prandtl  numbers. An increase in mean Nusselt number is found as the volume fraction  of nanoparticles increases for the whole range of Rayleigh numbers. In  addition, it is found that significant heat transfer enhancement can be  obtained by increasing thermal conductivity coefficient of additive  particles. At Ra=1.75×105, the Nusselt number increases by about 21% for  TiO2-Water, and almost 25% for Al2O3-Water, and finally around 40% for  Cu-Water nanofluid. Therefore, the highest values are obtained when using Cu  nanoparticles. The result obtained using variable thermal conductivity and  variable viscosity models are also compared to the results acquired by the  Maxwell-Garnett and the Brinkman model.