[kamal tewari]

Description


Single-stream swirling jet in still air

Swirl number: S = Wmax/Uo = 0.4
Exit Reynolds number: Re = 56,000

Introduction

The addition of swirl has large-scale effects on free jet development. In particular, the rate of mixing in-creases with swirl intensity. Thus swirling jets spread more quickly, and the mean velocities decay more rapidly than in a non-swirling jet. In a strongly swirling jet the gradients of static pressure set up across the flow field introduce adverse axial pressure gradients in the region of swirl decay, and these may be strong enough to cause reversal of the forward velocities near the jet axis. Thus a re-circulation zone is set up downstream of the jet orifice. Weaker swirl leads to less strong curvature of the stream lines, and the flow is then amenable to analysis as a thin shear layer. Even so, the spreading rate may reach as much as twice that of a non-swirling jet. The enhanced mixing resulting from the adverse pressure gradient leads to increases in the turbulence intensities. Further downstream, where the swirl field is weakened, the turbulence levels and the spreading rate reduce approximately to those of the non-swirling jet.

In this experiment values of U, V, W and all uiujbar were measured for swirl numbers: S = 0 and S = 0.31 for downstream distances up to x/D = 6. The external field was stationary. This test case involves the theoretical and experimental comparison between the variation of the centre-line values of U, uu and vv with x/D, as well as the decay of the maximum swirl velocity.


http://cfd.mace.manchester.ac.uk/cgi...html&1&0&0&0&0



I Am New to Fluent and want to analyse this problem kindly help me how to create mesh and set up boundary conditions,.