Search results for "Capillary Action"
showing 10 items of 179 documents
Field testing parameter sensitivity of the two-term infiltration equation using differentiated linearization
2003
Knowledge of soil hydraulic conductivity in the vadose zone is important in many agronomic, engineering and environmental areas. Transient tension infiltrometer experiments can be used to estimate the hydraulic conductivity, K0, corresponding to a given pressure head by the single-test (TST) method that uses the coefficients C1 and C2 of the two-term infiltration equation. The “Differentiated Linearization” (DL) method has been proposed to estimate these coefficients when a layer of contact material is used for the experiment. A field test of the DL and TST methods was conducted on a sandy loam and a clay soil. Eliminating the early-time influence of the contact layer was easy when the sorp…
Pressurized flow electrochromatography with reversed phase capillary columns
1995
Pressurized flow electrochromatography (PEC) is a hybrid of capillary LC and capillary electroendosmotic chromatography (CEC). Both a pressure gradient and an electric field are applied across a packed capillary. The feasability of a simple, easy to handle PEC instrumentation is demonstrated. Home made capillary columns with four different silica-based reversed phase packings have been operated under PEC conditions separating non ionic and ionic low molecular weight analytes. The capillary columns have been characterized with respect to their separation efficiency and selectivity and the results have been compared to those obtained with the purely pressure driven system. An electrochromatog…
Influence of temperature on the behaviour of small linear peptides in capillary electrochromatography
2000
The influence of temperature, T, on the retention times, peak widths, peak symmetry coefficients and theoretical plate numbers of two small linear peptides, [Met5]enkephalin and [Leu5]enkephalin, has been studied with capillary electrochromatography (CEC) capillary columns of 100 microm I.D. and 250 mm packed length with a total length of 335 mm, containing 3 microm Hypersil n-octadecyl bonded silica. With increasing column temperature from 15 to 60 degrees C, the electroosmotic flow (EOF) and the column efficiencies increased, whereas the retention coefficients (Kcec) of both peptides decreased. A linear relationship was found between the EOF value and the square root of the temperature ov…
Experimental assessment of the hydro-mechanical behaviour of a shale caprock during CO2 injection
2021
Abstract The presented experimental study focuses on the hydro-mechanical characterisation of a shale caprock (Opalinus Clay) in contact with carbon dioxide. The objective of this paper, consists in the evaluation of the material's sealing capacity in terms of entry-pressure, mechanical behaviour and sensitivity of the transport properties to chemo-mechanical effects induced by gaseous and liquid CO2 injection. Two types of Opalinus Clay core samples are tested; shaly and carbonate-rich. The sealing capacity has been evaluated on the shaly OPA according to the stepwise and the residual methods and compared to the results from mercury intrusion porosimetry. The obtained results and the diffe…
Der O2-Austausch zwischen Capillaren und Gewebe I. O2-Konzentrationsprofile in Blutcapillaren und deren Umgebung
1968
The differential equations valid for technical heat exchangers can also describe the O2 exchange in the blood capillaries and the exchange of molecules like THO and acetamid in the renal tubules. Differences in the boundary conditions occur, however. Hence, these differential equations were resolved for the corresponding boundary conditions. The results permit us to conclude that the concentration profiles occurring in the capillaries and renal tubules, as a result of diffusion in the capillary cross-section, can, generally speaking, be disregarded for the following reason: Although the differences in partial pressure between the capillary wall and capillary centre, at the beginning of the …
A model of capillary phenomena in RN with subcritical growth
2020
This paper deals with the nonlinear Dirichlet problem of capillary phenomena involving an equation driven by the p-Laplacian-like di¤erential operator in RN. We prove the existence of at least one nontrivial nonnegative weak solution, when the reaction term satisfies a sub-critical growth condition and the potential term has certain regularities. We apply the energy functional method and weaker compactness conditions.
Dimensional analysis and upscaling of two-phase flow in porous media with piecewise constant heterogeneities
2004
Dimensional analysis of the traditional equations of motion for two-phase flow in porous media allows to quantify the influence of heterogeneities. The heterogeneities are represented by position dependent capillary entry pressures and position dependent permeabilities. Dimensionless groups quantifying the influence of random heterogeneities are identified. For the case of heterogeneities with piecewise constant constitutive parameters (e.g., permeabilities, capillary pressures) we find that the upscaling ratio defined as the ratio of system size and the scale at which the constitutive parameters are known has to be smaller than the fluctuation strength of the heterogeneities defined, e.g.,…
Capillary Waves in a Colloid-Polymer Interface
2004
The structure and the statistical fluctuations of interfaces between coexisting phases in the Asakura-Oosawa (AO) model for a colloid--polymer mixture are analyzed by extensive Monte Carlo simulations. We make use of a recently developed grand canonical cluster move with an additional constraint stabilizing the existence of two interfaces in the (rectangular) box that is simulated. Choosing very large systems, of size LxLxD with L=60 and D=120, measured in units of the colloid radius, the spectrum of capillary wave-type interfacial excitations is analyzed in detail. The local position of the interface is defined in terms of a (local) Gibbs surface concept. For small wavevectors capillary wa…
Effects of finite thickness on interfacial widths in confined thin films of coexisting phases
1999
The capillary broadening of a 2-phase interface is investigated both experimentally and theoretically. When a binary mixture in a thin film with thickness D segregates into two coexisting phases the interface between the two phases may form parallel to the substrate due to preferential surface attraction of one of the components. We show that the interfacial profile (of intrinsic width w0) is broadened due to capillary waves, which lead to fluctuations, of correlation length of the local interface positions in the directions parallel to the confining walls. We postulate that acts as an upper cutoff for the spectrum of capillary waves on the interface, so that the effective mean square inter…
Nucleation and cavitation in parahydrogen
2012
We have used a density functional approach to investigate thermal homogeneous nucleation and cavitation in parahydrogen. The effect of electrons as seeds of heterogeneous cavitation in liquid parahydrogen is also discussed within the capillary model. (C) 2011 Elsevier B.V. All rights reserved.