Figure 8. Thermally insulated boundaries (purple) assumed for CFD analyses.

The near-wall static pressures of the fluid computed for the above described case are illustrated in Figure 9. These pressures are relative to an arbitrary value of zero assumed for the (yellow) outlet surface of the flow channel. For this case the annular gap between the sleeve and the stationary hard face is about 2 mm. The conical pressure surfaces are displaced 127 microns from the rotating (foreground) and stationary (background) axially tapered boundaries (Figure 2). Due to the symmetry of the flow about the centerplane of the channel, it is possible to display only one axial end of the pressure field to obtain a complete representation of both inboard and outboard sides of the solution. The symmetry of the flow is caused by a weak coupling between the governing equations of fluid motion and thermal energy brought about by the small variations in the thermofluid properties of water over the temperature range of the problem. The predominately blue colored surface in the foreground represents the fluid pressure near the rotating sleeve. Contrasting this

Figure 9. Pressure surfaces near rotating sleeve (foreground) and seal face.

relatively lower-pressure surface is the predominately yellow higher-pressure surface near the stationary seal face. Aside from the obvious radial gradient of fluid pressure created by centrifugal forces within the flow, milder and more localized axial and circumferential gradients are also noticeable, particularly over the outer pressure surface adjacent to the non-rotating seal face boundary.

Figure 10 shows a similar view, this time of the velocity field within the same near-wall conical surfaces depicted in Figure 9. Here, the length of the flow vectors is proportional to the local magnitude of the fluid velocity. Not surprisingly, the vectors (colored by fluid speed for quantitative reference) align closely with the rotational direction of the sleeve, with both axial and radial gradients being clearly visible. Near the rotating wall the flow velocity increases dramatically in the axial direction from the region near the channel to

Figure 10. Flow velocity vectors near rotating sleeve and stationary seal face.

the region near the interface, closest to the viewer. The highest flow speeds shown here are about two-thirds of the corresponding local surface speed of the rotating sleeve. The flow at the larger radius near the stationary wall (background) decelerates sharply between the interface region and the near-channel region. As expected, the flow field demonstrates a strong radial dependence, being much greater near the rotating inner boundary of the domain.

Shown in Figure 11 is a magnified view of the same velocity vectors, looking radially inward just above the outlet of the domain. The vectors to the left of the outlet are near the rotating sleeve (smaller radius), while those on the right side are near the outboard stationary seal face. The significant point to note here is the clear leftward inclination of both sets of flow vectors, suggesting axial circulation of the fluid.

Figure 11. Radially-inward view of flow vectors near barrier fluid outlet.

The near-wall turbulent kinetic energy of the flow is shown in Figure 12. Here again the data in the foreground correspond to the fluid later near the rotating sleeve, while on the other side of the channel the data represent the fluid layer near the stationary seal face. Notice that the turbulence levels are highest near the regions of the domain where abrupt geometric changes in radial cross-section occur, namely near the channel and the sliding