MHD mixed convection and entropy generation in a lid-driven cavity with rotating cylinders filled by a nanofluid using two phase mixture model

In this study, mixed convection and entropy generation in a square cavity containing nanofluid subjected to magnetic field has been studied. A two-phase model (mixture) was used to simulate Newtonian fluid flow and heat transfer in a cavity with rotating cylinders. The Richardson and Hartman numbers ranges are 1 ≤ Ri ≤ 100 and 0 ≤ Ha ≤ 30 respectively. The laminar, two-dimensional (2D), steady and Newtonian flows are assumptions that are considered in this study. The angle of cavity (θ) and dimensionless angular velocity of cylinders (Ω) ranges are 0° ≤ θ ≤ 90° and −3 ≤ Ω ≤ −1 respectively. The effect of insulation and isothermal (T = T_c) cylinders on the flow field and heat transfer has been investigated. The distribution of nanoparticles inside the cavity for different Hartman numbers and Richardson numbers also is investigated. In addition, the effect of the presence of the cylinder on the cavity in stationary and rotating states on the flow field and the increase of the heat transfer rate has been studied. Average and local Nusselt number in terms of Hartman numbers, volume fractions, angles of cavity, isothermal (and adiabatic of cylinders) and angular velocity of cylinders were obtained. The effect of the magnetic field intensity on total entropy generation has been investigated. It's found that by reducing Hartmann number, reducing Richardson number and increasing volume fraction, heat transfer will increase. The presence of the cylinder and its angular velocity also improve the heat transfer. In addition, isothermal cylinders will have a great effect on increasing heat transfer.