By using the teeth for immobilisation and employing incident light microscopy at magnifications up to 240 X, entire capillary beds could be observed in the labial gingiva in small laboratory animals. In the mandibular incisor region, simple capillary loops, as found in the human gingiva and nail bed, were absent in all species examined except in some guinea pigs. In the hamster, where the topog...

In this article, we demonstrate a numerical 3-D chip, and studied the capillary dynamics inside the microchannel. We applied the level set method on the Navier-Stokes equation which incorporates the surface tension and two-phase flow characteristics. We analyzed the capillary dynamics near the junction of two microchannels. Such a highlighting point is important that it not only can provide the...

On-line coupling of an automated flow system with a commercially available capillary electrophoresis (CE) system with an electrospray interface (ESI) for mass spectroscopic (MS) detection is described. The peculiarities of CE-ESI-MS interfaces, in which a high electrical field must be applied to the capillary end where the sample is provided by the flow system, introduce significant difficultie...

A mesoscopic or coarse-grained approach is presented to study thermocapillary induced flows. An order parameter representation of a two-phase binary fluid is used in which the interfacial region separating the phases naturally occupies a transition zone of small width. The order parameter satisfies the Cahn-Hilliard equation with advective transport. A modified NavierStokes equation that incorp...

Analysis of the linear theory of capillary instability of threads of Maxwell fluids of diameter D is carried out for the unapproximated normal mode solution and for a solution based on viscoelastic potential flow. The analysis here extends the analysis of viscous potential flow [Int. J. Multiphase Flow 28 (2002) 1459] to viscoelastic fluids of Maxwell type. The analysis is framed in dimensionle...

Light-based flow systems for point-of-care devices are of interest because, in principle, sunlight could be used to operate them, potentially allowing for high functionality with minimal device complexity and expense. A light-operated method to drive flow using poly(N-isopropylacrylamide), a 'smart' polymer that changes wettability as a function of temperature, is introduced. It is grafted onto...

Capillary instability of a viscous fluid cylinder of diameter D surrounded by another fluid is determined by a Reynolds number J = V D `= `, a viscosity ratio m = a= ` and a density ratio ` = a= `. Here V = = ` is the capillary collapse velocity based on the more viscous liquid which may be inside or outside the fluid cylinder. Results of linearized analysis based on potential flow of a viscous...

This work explores capillary flow through micropillar arrays with rectangular pillar arrangements. The effects of these configurations on permeability and capillary pressure are investigated for heat pipe wick applications. The permeability is described in terms of three dimensionless parameters: h=d; l=d, and S=d, where l and S are the edge-to-edge spacings in the xand y-directions, respective...

This Article describes the use of capillary pressure to initiate and control the rate of spontaneous liquid-liquid flow through microfluidic channels. In contrast to flow driven by external pressure, flow driven by capillary pressure is dominated by interfacial phenomena and is exquisitely sensitive to the chemical composition and geometry of the fluids and channels. A stepwise change in capill...