Numerical Study of the Influence of Dynamic and Thermal Exit Conditions on Axisymmetric Laminar Buoyant Jet

We propose in our article numerical solutions of the Navier-Stokes equations governing the buoyant round laminar jet. The purpose of this work is to study the influence of the exit conditions at the nozzle exit on the dynamic and thermal parameters of the vertical jet flow. Two emission cases have been considered: Velocity and temperature are uniform or parabolic. The numerical code developed uses a finite difference scheme. The numerical results have been compared with those given by Martynenko, who considered in his analysis only two integration constraints: the momentum at the nozzle exit and the conservation of the energy transported by the jet flow. The obtained results are in good agreement with those proposed in the literature in the plume zone, in which the emission conditions are ignored, and the jet flow is governed mainly by the buoyancy forces. We propose in this paper a correlation to predict the axial virtual origin Xp of the plume zone. Experiments were conducted to validate the numerical model using a nonintrusive method, namely, laser doppler velocimetry.