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The flow and heat transfer of Al2O3–water nanofluid in a channel partially filled with porous media is investigated numerically. The turbulence effect in the porous media is taken under consideration in this article. A simple case is simulated first to evaluate the accuracy of the results in comparison with the available data. The turbulent kinetic energy profile is investigated at a flow cross section. The results show that the maximum turbulent kinetic energy occurs in the clear fluid region in the vicinity of the porous media region. The turbulent kinetic energy is a decreasing function of the porosity of the porous medium. The effect of porosity on the variation of turbulent kinetic energy decreases with the increase in the porosity of the porous medium. The turbulent kinetic energy in clear fluid and porous media regions decreases with the increase in nanofluid concentration from 0.01 to 0.03, and it increases with the increase in nanofluid concentration from 0.03 to 0.05. The temperature of the nanofluid increases with the increase in the nanofluid concentration and decrease in the porosity of porous media. It is shown that for this case, with the increase in nanofluid concentration and porosity of porous media, the skin friction coefficient increases and the Nusselt number decreases.

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The pollutant dispersion from a small cooling tower is numerically investigated in the current study. The behavior of exhaust plume from a grooved cooling tower is studied to control the dispersion of pollutant by swirling the plume. The pollutant concentration, i.e., mass of pollutant per unit mass of the mixture, and the plume rise, i.e., the geometric loci of the highest pollutant concentration points at each flow cross sections downstream of cooling tower, are investigated as significant parameters in the problem of pollutant dispersion from sources of air pollution. The various ways by which the counterrotating vortex pair as well as swirling plume affect the behavior of outflow from source of air pollution are investigated. An innovative structure for inner side of cooling tower by cutting the angular grooves is proposed in this article for reduction in pollutant concentration on the ground level and moving the plume rise to the higher altitude. The results indicate that the minimum value of pollutant concentration on the ground level is obtained by applying parallel grooves with respect to the axis of the cooling tower and the plume rise occurs in a higher altitude by increasing in the angle of the grooves. The physics of the outflow from the tower is investigated to examine the effects of the grooves angle on the path of plume and dispersion of pollutant.