We revisit Taylor dispersion in oscillatory flows at zero Reynolds number, giving an alternative method of calculating the Taylor dispersivity that is easier to use with computer algebra packages to obtain exact expressions. We consider the effect of out-of-phase oscillatory shear and Poiseuille flow, and show that the resulting Taylor dispersivity is independent of the phase difference. We als...

Recently, Roht et al. [J. Contam. Hydrol., 2013, 145, 10-16] observed that the presence of suspended non-Brownian macroscopic particles decreased the dispersivity of a passive solute, for a pressure-driven flow in a narrow parallel-plate channel at low Reynolds numbers. This result contradicts the idea that the streamline distortion caused by the random diffusive motion of the particles increas...

[1] Gas phase miscible displacement experiments were conducted to quantitatively investigate the advective and dispersive contributions to gas phase transport in unsaturated porous media over a range of soil water contents. Furthermore, the independence of measured dispersivity values was evaluated through comparison of nonreactive and reactive tracer transport. Methane was used as a nonreactiv...

A major contaminant transport process in soils is hydrodynamic dispersion by affecting the spreading and arrival of surface-applied pollutants at underlying groundwater reservoirs. When a soil unsaturated, very much affected water saturation. Centimeter- decimeter-scale column experiments were carried out to explore effects fluid saturation particle size on unsaturated solute dispersivity. Meas...

The coefficients of dispersion, Dij , and the dispersivity, aijkl , appear in the expression for the flux of a solute in saturated flow through porous media. We present a detailed analysis of these tensors in an axially symmetric porous medium and show that in such a medium, the dispersivity is governed by 6 independent moduli. We present also the constraints that have to be satisfied by these ...

this paper presents a simple yet powerful original approach for approximating dispersivity in porous media. the key to this approach is both use of least-squares criterion and image processing technique. two dimensional transparent models, including horizontal and vertical configurations, under different combinations of grain sizes and pore velocities, experimented. concentration data were obta...

The effects of binder chemistry on electrical-conductivity development, i.e., dynamic percolation, in carbon nanotube (CNT)-filled epoxy-based pastes during curing were investigated. electrical resistivities the are influenced not only by dispersivity CNT filler but also pastes. electrical-conductivity-development kinetics accelerated introducing a reactive diluent, namely phenyl glycidyl ether...

Anomalous dispersion is observed throughout hydrology, yielding a contaminant plume with heavy leading tails. The fractional advection dispersion equation (FADE) captures this behavior by replacing the second-order spatial derivative with a Riemann-Liouville (RL) fractional derivative. The RL fractional derivative is a nonlocal operator and models large jumps of solute particles in heterogeneou...

• Coupled topography- and salinity-driven groundwater flow is studied on basin-scale. Increase in salinity/anisotropy weakens the topography-driven forced convection. Permeability/dispersivity modify coupling between salt- freshwater zones. Flow salt transport are revealed separated aquifers through faults. Mixed topohaline convection evolves a basin-scale system. Salinization of has endangered...