Laminar Plumes from a Line Source and Their Possible Flow Behaviours

Abstract

Numerical investigation on laminar plumes that under goes buoyancy reversal had just been made, fixing both Re & Pr and varying Fr during the simulations. Water density was taken as a quadratic function of temperature. The result showed some side-to-side apping and bobbing motion after the core of the fountain were exposed together with head detachment behaviour. At the fountains core, profiles of vertical velocity component show that decrease in vertical velocity with height is not smoother even at higher Froude numbers as compared to the case in our previous study for (Re = 50). Empirically determined scalings laws for fountain height and time to attain maximum height were obtained. Initially rising plumes were symmetric and takes much longer time to attain a fully developed stage as Fr increases before sufficient dense fluid is produced to halt their rise. Generally, we can conclude that with the quadratic dependence relation assumption, Irrespective of the ow parameters used within the Reynolds number range 50 \(\le\) Re \(\le\) 100 and Prandtl number Pr = 7&11:4 the ow behaviour remains the same. Except for the behaviour in the profiles of vertical velocity that show some slight differences as compared to our earlier investigation, and the Froude number that represents the balance between inertia and buoyancy forces (responsible for the variation in the fountains heights).