The effect of the anionic surfactant sodium dodecyl sulfate (SDS) on Pseudomonas fluorescens biofilms was investigated using flow cell reactors with stainless steel substrata, under turbulent (Re = 5200) and laminar (Re = 2000) flow. Steady-state biofilms were exposed to SDS in single doses (0.5, 1, 3 and 7 mM) and biofilm respiratory activity and mass measured at 0, 3, 7 and 12 h after the SDS...

Hemodynamic shear stress, the frictional force acting on vascular endothelial cells, is crucial for endothelial homeostasis under normal physiological conditions. When discussing blood flow effects on various forms of endothelial (dys)function, one considers two flow patterns: steady laminar flow and disturbed flow because endothelial cells respond differently to these flow types both in vivo a...

This article studies nonatomic congestion games with symmetric players sending flow in arcs linking a unique source and destination. These games can represent systems where electricity retailers controlling flexible consumption minimize their energy costs. We focus on games with affine cost functions and define laminar Nash equilibrium where the constraints on the minimum and maximal flow that ...

We consider the laminar flow of a vortex crystal in the Corbino disk geometry. Laminar flow can be induced by thermal fluctuations melting the crystal, but also by shear stress after applying a large current at zero temperature. While the velocity profile is the same in the two cases, the underlying vortex structure is completely different. A vortex crystal in this geometry can flow in a lamina...

An easy-to-interpret kinematic quantity measuring the average corotation of material line segments near a point is introduced and applied to vortex identification. At a given point, the vector of average corotation of line segments is defined as the average of the instantaneous local rigid-body rotation over ‘all planar cross-sections’ passing through the examined point. The vortex identificati...

Laser-Doppler velocity measurements adjacent to the bounding walls of three-dimensional (3-D) backward-facing step flow are performed for the purpose of mapping the boundaries of the reverse flow regions that develop in this geometry (adjacent to the sidewalls, the flat wall and the stepped wall) as a function of the Reynolds number. The backward-facing step geometry is configured by a step hei...

This paper describes laminar fluid flow through a three-dimensional elastomeric microstructure formed by two microfluidic channels, fabricated in layers that contact one another face-to-face (typically at a 90 degree angle), with the fluid flows in tangential contact. There are two ways to control fluid flow through these tangentially connected microchannels. First, the flow profiles through th...

The history of Laminar Flow Control (LFC) from the 1930s through the 1990s is reviewed and the current status of the technology is assessed. Early studies related to the natural laminar boundary-layer flow physics, manufacturing tolerances for laminar flow, and insect-contamination avoidance are discussed. Although most of this publication is about slot-, porous-, and perforated-suction LFC con...

Laminar and Turbulent Flow. If a fluid flows through a long, smooth-walled, narrow tube at a low flow rate, flow is likely to be “laminar.” Here the particles of fluid travel parallel to the sides of the tube. This is often the case for blood flowing in veins. Flow is proportional to the pressure difference (Figure 2A). The viscosity of the fluid is an important determinant of the relationship ...