Effect of the coflow stream on a plane wall jet

International audienceWe propose in this work to study an isothermal and a non-isothermal laminar plane wall jet emerging in a coflow steam. The numerical solution of the governing equations was performed by a finite difference method. In this work, we are interested in the study of the influence of Grashof numbers on the wall jet emerging in a medium at rest. Further, we will examine the effect of the coflow stream on the behavior of the dynamic and thermal properties of the wall jet subjected to a constant temperature. A comparison with a simple wall jet is carried out. The results show that for a buoyant wall jet, two parameters can influence the flow: the inertial and buoyancy forces. The velocity effect indicates that the potential core length increases with the velocity ratio. We are also showed that when using a momentum length scale, the normalized longitudinal maximum velocity can reach an asymptotic curve at different velocity ratios

A numerical study of a plane turbulent wall jet in a coflow stream

International audienceThis work is a numerical study of an isothermal and a non-isothermal turbulent plane wall jet emerging in a coflow stream with different velocity ratios ranging from 0 to 0.2. Turbulence modeling is performed by using a modified low-Reynolds number k-epsilon model. The numerical resolution of the governing equations was carried out via finite difference method. The present predictions are compared with those suggested in the literature. It was found that the studied model reasonably predicts the mean flow proprieties of the flow field. The main purpose of this work is to determine the influence of the velocity ratio on the dynamic; thermal and turbulent characteristics of the flow A comparison with a simple wall jet is made. Besides, the influence of Reynolds and Richardson numbers on the wall jet emerging in a coflowing stream is examined. As far as the isothermal flow is concerned, results show that the potential core length decreases in accordance with the velocity ratio. It was also found that, downstream from the jet exit (in the established region), the longitudinal distributions of the normalized forms of the excess maximum x-velocity and the turbulent maximum kinetic energy converge to a single curve at different velocity ratios. The present investigation suggests that the effect of coflowing jet on the dynamic, thermal and turbulent parameters is negligible in the potential core area (ZFE) and the jet is similar to that of a simple jet. Further downstream of this region, the velocity ratio affects the flow as far as the high coflow streams are concerned. (C) 2016 International Association for Hydro-environment Engineering and Research, Asia Pacific Division. Published by Elsevier B.V. All rights reserved