The transition characteristics of flows are investigated. Both transition of laminar to transitional flow and transitional flow to fully turbulent are looked into. As a first case, the flow past a flat plate is considered. Two-dimensional flow is assumed for computational simplicity. Large eddy simulation is employed without any sub-grid scale eddy viscosity model. One would expect this to yield same results in the laminar region and differ from the actual solution in the other regions. The velocity fluctuations and other variables are obtained and analyzed. One of the important variables is the vorticity. This is non-dimensionalized using y, the normal distance from the wall as the vorticity Reynolds number Reξ= ξy2/n. . It is seen that at a particular streamwise (x) location, the Reξ is zero at the wall and reaches a maximum and goes to zero at the edge of the boundary layer. The average value in the normal (y) direction is plotted against Reξ. The same is repeated with the maximum value of Reξ at an x location, and this is also plotted against Rex. It is seen that the two transition points can be obtained from either of these two graphs. Reynolds stresses and root mean square of velocity fluctuations are also observed of exhibiting similar behavior. Finally, the Smagorinsky constant is varied linearly between the two transition points and the effect is looked into. Further work needs to be carried out to see if the transition values of Reξ are universal. The next step would be to extend the study to three dimensional flows.
