Radial Wall Jet Flow Over Sigmoidal Surfaces

Radial wall jet flows across flat smooth surfaces have been studied for decades. These studies show that the radial velocity of these jets decays inversely with distance from the nozzle with modest contribution from friction (Poreh, et al., 1967; Rajaratnam, 1976). However, the extent to which flat surface results apply to curved surfaces remains unclear. In this paper we explore the influence of settled particle bed slope on radial wall jet velocity profiles. Jet flows over particle beds often introduce curvature in the particle bed profile, but the influence of the developed curvature on the velocity profile has not been explored. We model the step change in thickness as a sigmoidal curve of variable steepness and use conservation of momentum to evaluate the velocity profile for steady fixed beds. We find that surface curvature has a significant influence on the velocity decay coefficients, provided there is a slip velocity in the vicinity of the particle bed interface, which is strictly true for particle surfaces. We show that the velocity profile attenuates because of curvature. Indeed, conservation of momentum predicts conditions where the forward momentum of the flow is directed completely upward. The solution identifies two new dimensionless groups that determine whether a curved surface is sufficient to block radial flow and force flow vertically.

Versatile additively manufactured (3D printed) wall-jet flow cell for high performance liquid chromatography-amperometric analysis: application to the detection and quantification of new psychoactive substances (NBOMes)

Additive manufacturing is an emerging technology of vast applicability, receiving significant interest in a plethora of industrial and research domains as it allows the translation of designs produced via computer software, into 3D printed objects.

Flow Analysis of Laminar Wall Jet over Curved Cavity with a Channel Mounted Fin

Wall jet flow is used for industrial cooling process, cooling of electronic component mounted on circuit board etc. Numerical simulations have been carried out for laminar two dimensional wall jet flows along curved cavity having a channel mounted thin fin. The commercial finite volume code FLUENT is chosen to resolve the mass balance and momentum balance equations. Fluid flow characteristics are investigated for different Reynolds number (Re=100 to 600) and for different fin geometry. The results are plotted in the form of velocity profiles and streamline contours. The effect of fin length on the laminar wall jet characteristics is also investigated.

Scour at Bridge Foundations in Supercritical Flows: An Analysis of Knowledge Gaps

The scour at bridge foundations caused by supercritical flows is reviewed and knowledge gaps are analyzed focusing on the flow and scour patterns, available measuring techniques for the laboratory and field, and physical and advanced numerical modeling techniques. Evidence suggests that the scour depth caused by supercritical flows is much smaller than expected, by an order of magnitude compared to that found in subcritical flows, although the reasons for this behavior remain still unclear. Important questions on the interaction of the horseshoe vortex with the detached hydraulic-jump and the wall-jet flow observed in supercritical flows arise, e.g., does the interaction between the flow structures enhance or debilitate the bed shear stresses caused by the horseshoe vortex? What is the effect of the Froude number of the incoming flow on the flow structures around the foundation and on the scour process? Recommendations are provided to develop and adapt research methods used in the subcritical flow regime for the study of more challenging supercritical flow cases.