Turbulent Jet Results

Plot the axial velocity of the turbulent jet at the centerline by going to Plots - XY Plot. Select the options as in the dialogue below. Make sure to select the centerline surface as the surface to plot the velocity along.

The centerline axial velocity should look like this:

It is clear that the axial velocity decreases with increasing distance from the jet. However, comparing this plot to the centerline velocity in the laminar case, the turbulent case has an initial development region, where the velocity takes a longer distance to start decaying.  

Similarly, create a plot of the turbulent kinetic energy k along the centerline: adjust the XY Plot dialogue box to have Y axis function Turbulence - Turbulent kinetic energy (k). The plot is below.

The turbulent kinetic energy is the mean kinetic energy per unit mass in the fluctuating velocity field. It is governed by a production term P, a dissipation term -ε, mean flow convection -Dk/Dt, and turbulent transport -grad(T). The peak in turbulent kinetic energy just after the inlet is due to the production term (affected by fluid shear or friction) dominating; the turbulent kinetic energy again approaches zero as the distance from the inlet increases as the fluid is convected and dissipated away from the centerline into the surroundings.

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