Jespersen and Levit computed the viscous incompressible flow about a tapered cylinder. This computation features unsteady vortex shedding at a Reynolds number of 150 based on the mid-span cylinder radius. The mesh used is wraps around the cylinder producing a radial structure that does not quite close upstream.

The results from the simulation are a series of snap-shots in time saved to disk. The time-step between these saved frames is too large for the series to be used for post-processing with this explicit scheme -- not every iteration is available. One frame was selected and run as a steady-state problem. The inviscid incompressible residence-time formulation was used -- the viscous stresses were not available. The results therefore are not entirely physical but can provide some insight and are displayed.

The base (with contour lines of residence-time) and the tapered cylinder are rendered in gray. Neither the base of the top of the simulation are treated with a no-slip condition. The contour lines are of equal spacing in and are roughly parallel (perpendicular to the flow direction) upstream of the post. This indicates undisturbed flow. The effect of the vortices in the wake of the post is obvious when examining the contours of the shadow region. These higher contour values are a reflection of the slower moving flow and the fluid trapped in the (unmoving) vortices. An isosurface is seen at about the characteristic time for the problem. This surface clearly depicts the wake deficit downstream and can also be seen attached to the backside of the cylinder where the flow has been trapped.

Data courtesy of NASA Ames Research Center.