Showing 2 results for Heat Transfer Enhancement
M. Kahrom, A. Farahbode, and D. Khodadadzadeh,
Volume 27, Issue 1 (7-2008)
Abstract
A rectangular rod is placed in a flow field flowing parallel to a flat plate. Effect of chord-thickness ratio of rectangular rod on developing vortex shedding downstream to the rod is studied. Then, for each one of the aspect ratios, the distance of the rod from the neighboring flat plate is reduced until the rod sticks to the flat plate. In each case, the effect of the flat plate boundary layer on Strouhal number and the contrary effect of the boundary layer on vortex shedding from the rectangular rod are studied. Results show that as the rectangular rod enters into the flat plate boundary layer, vortex generation from the closest side of the rod reduces, thereby reducing the Strouhal number as well. Finally, when the rectangular rod sticks to the flat plate, a stationary wake forms downstream the rod and sticks to the flat plate. Meanwhile, the boundary layer over the flat plate is disturbed effectively and heat transfer coefficient from the flat plate is enhanced by an average of 50% and up to 200% in some places, locally.
A. R. Rahmati , E. Kashai,
Volume 40, Issue 2 (1-2022)
Abstract
A two-phase lattice Boltzmann model considering the interaction forces of nanofluid has been developed in this paper. It is applied to investigate the flow and natural convection heat transfer of Al2O3–H2O nanofluid in an enclosure containing internal heat generation. To understand the heat transfer enhancement mechanism of the nanofluid flow from the particle level, the lattice Boltzmann method is used because of its mesoscopic feature and numerical advantages. By using a two-component lattice Boltzmann model, the heat transfer enhancement of the nanofluid is analyzed through incorporating the different forces acting on the nanoparticles and the base fluid . The effects of interaction forces, nanoparticle volume fractions (0.0-0.05), and internal and external Rayleigh numbers (103-106) on the nanoparticle distributions and heat transfer characteristics are investigated. The average Nusselt number increases with the increase of nanoparticle volume fraction and Rayleigh number. We also compared and analyzed adding internal heat generation on the nanoparticles and the base fluid separately, and it was found that by considering heat generation on the base fluid, it mostly affects the temperature field, and by considering that on nanoparticles, it mostly affects the stream field.
