Numerical Study of Mixed Convection of Buoyant Twin Jet

Abstract

The effect of mixed convection of twin vertical jets is investigated numerically in this paper. The results are presented specifically for flows affected by buoyancy for two parallel jets of same velocities ranging between 0.25 m/s and 5.0 m/s and temperatures between 295 K and 320 K. Both jets generate a slow flow with a temperature difference (with the ambient flow) less or equal to 32 °C (305 K). Predictions of dynamical and thermal parameters are obtained for the merging and combining regions. This study reveals that the trajectory of the two jets is strongly influenced by the ratio of buoyancy to inertial forces. Results indicate that, relative to isotherm jets, the location along the vertical symmetry plane at which the two jets merge (merging point) decreases with increasing jet inlet temperature. It was also found that the location of the merging point is shifted toward the confining wall as the velocity of the jets increases. The behavior law (linear regression), relating to the expansion of the jet, is not verified in the developed region for each value of the inlet velocity and temperature. This is explained by the fact that natural convection is more predominant than forced convection. The results show that the self-similarity of the cross profiles of the mean velocity and the behavior law relating to the expansion of the jet are obtained throughout the developed region.