A numerical study of mixed convection in a square enclosure from a heating element to a cold moving wall is performed under the isothermal heating conditions. The heater is placed at the bottom boundary and the cold upper wall moves horizontally towards right side with constant velocity. The lateral walls are insulated. The study includes the thermal performance of nanofluid for various shaped obstacles kept at center of the enclosure. The application of hydro-magnetism with uniform and constant magnetic intensity throughout the bottom wall is considered. The heat convection is studied at two Richardson number (0.01 and 10), four percentage volume of silver nanoparticles (0%, 2%, 5%, and 8%) and four Hartmann number (0, 10, 20, and 50). Grashof number, Prandtl number, and Reynolds number have a constant value of 104, 6.2 and 100 respectively. The obtained results indicate the suppression of heat fluxes with increasing intensity of magnetic field whereas it increases with increasing Richardson number and percentage volume of the nano-material in the base fluid.
A computational study of laminar and steady heat transfer is carried out with copper (Cu)-water nanofluid inside a lid driven cavity. Different conducting obstacles are placed at the optimum position for which the maximum thermal transport occurs. The thermal performance of the Cu-H2O nanofluid is found out at this optimum position with three different cylinder geometries (square, rectangular and circular), two Richardson numbers (0.01 and 1), and three volume concentrations of copper nanoparticles (0 %, 3 % and 5 %) in water. The Prandtl and Grashof numbers are considered as 6.2 and 10 4 , respectively. The fluid is heated by placing a differential heater at the left wall. All the walls except the upper one are in a stationary condition. The top moving wall, stationary bottom wall and the remaining portion of the left wall, where there is no heater, are made insulated. The rectangular cylinder is placed at two different orientations (vertical and horizontal). The results show that the shape of the cylinder contributes to a compelling role in efficient heat transfer. For both Richardson numbers, the Nusselt number is maximum with the case where the square-shaped cylinder is placed at the top left corner. The Nusselt number increases with an increase in the percentage volume of nanoparticles and reduces with an increase in the Richardson number.
This paper investigates free convection in a partially heated square cavity filled with alumina-water nanofluid. The investigation is carried out at the three-volume fraction of nanoparticles (0, 0.03, 0.05), two Prandtl numbers (2.66, 6), and constant Grashof number (105) with three shapes of insulating obstacles (Square, Circular, and Rectangular). The results show that the nanofluid volume fraction and Prandtl number significantly enhance the heat transfer. The user-defined function (UDF) is developed and computed to investigate the effect of nanoparticle diameter and its temperature-dependent viscosity on convection. The average Nusselt number (Nu) increased with the temperature-dependent viscosity model and by increasing the percentage concentration of the nanoparticles. For all obstacle shapes, the thermal performance improved with increase in the nano-particle diameter.
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