Secondary vortices in swirling flow

Twisted tapes are used to induce swirling flow and improve mixing. The flow induced by a 180 degree twisted tape with length (pitch) 60 mm and diameter 25.4 mm in a circular pipe was investigated using Laser Doppler Velocimetry (LDV) measurements. Tangential velocity profiles downstream of the twisted tape swirler were measured at multiple locations along the pipe axis, across the horizontal diameter of the pipe. The profiles showed an unexpected transition along the pipe axis from regular swirling flow to an apparent counter-rotation near the pipe axis, and then reverting back to regular swirling flow. Injecting fine air bubbles into the flow showed the existence of two co-rotating helical vortices superimposed over the main swirling flow. The close proximity of the two co-rotating vortices creates the local reversing flow at the pipe centerline. The secondary vortices are analyzed with high speed camera videos and numerical simulations.Comment: 2 videos include

Cellular Blood Flow

The fluid dynamics video that is presented here outlines recent advances in the simulation of multiphase cellular blood flow through the direct numerical simulations of deformable red blood cells (RBCs) demonstrated through several numerical experiments. Videos show particle deformation, shear stress on the particle surface, and the formation of particle clusters in both Hagen-Poiseuille and shear flow.Comment: 2 pages, one hyperlink to 2 video

Effects of CD pressure variations on coat-weight nonuniformities

"November 1991.""Submitted for publication in AICHE Journal.

Free edge flutter based on 3-D structural characteristics of paper

"May 1995.""Submitted to Journal of Pulp and Paper Science and TAPPI Engineering Conference, September 11-14, 1995, Dallas, Texas.

Effect of Fluid Shear Stress on Endocytosis of Heparan Sulfate and Low-density Lipoproteins

Hemodynamic stress is a critical factor in the onset of atherosclerosis such that reduced rates of shear stress occurring at regions of high curvature are more prone to disease. The level of shear stress has direct influence on the thickness and integrity of the glycocalyx layer. Here we show that heparan sulfate, the main component of the glycocalyx layer, forms an intact layer only on cell surfaces subjected to shear, and not under static conditions. Furthermore, receptor-mediated endocytosis of heparan sulfate and low-density liporoteins is not detectable in cells exposed to shear stress. The internalized heparan sulfate and low-density lipoproteins are colocalized as shown by confocal imaging