Related Experiment Video
Updated: Jul 11, 2026
06:55
Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level
Published on: September 26, 2016
An interpretation of potential scale dependence of the effective matrix diffusion coefficient
1Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States. hhliu@lbl.gov
Journal of Contaminant Hydrology
|October 28, 2006
Summary
Scale-dependent matrix diffusion in fractured rock is influenced by local flow loops and fracture geometry. Numerical experiments reveal these factors enhance the effective matrix diffusion coefficient with increasing test scale.
Area of Science:
- Geosciences
- Hydrogeology
- Rock Mechanics
Background:
- Matrix diffusion is crucial for solute transport in fractured rock.
- Previous field tracer tests show enhanced effective matrix diffusion coefficients with increasing scale.
Purpose of the Study:
- Investigate mechanisms behind scale-dependent matrix diffusion.
- Understand the influence of flow path geometry and local flow loops.
Main Methods:
- Numerical experiments simulating solute transport in fractured rock.
- Discrete fracture network flow simulations for water velocity distribution.
- Particle-tracking scheme and impulse-response function for solute transport calculation.
- Matching breakthrough curves to analytical solutions for parameter up-scaling.
Main Results:
- Local flow loops and matrix diffusion contribute to scale dependence.
- Scaling properties of flow path geometry play a significant role.
- Effective matrix diffusion coefficient increases with test scale.
Conclusions:
- A combination of local flow loops, matrix diffusion, and geometric scaling explains observed scale dependence.
- Numerical experiments provide insights into up-scaled transport parameters.
Related Concept Videos
01:24Protein Diffusion in the Membrane
Proteins show rotational as well as lateral diffusion across the membrane. The lateral diffusion of proteins was confirmed through the cell fusion experiment where mouse and human cells were fused, resulting in hybrid cells. When the human and mouse cells fused, the specific membrane proteins on human and mouse cells were marked with the red and green-fluorescent markers, respectively. Initially, the red and green fluorescence was located on the respective hemisphere of the cell. As time...
01:13Force and Potential Energy in One Dimension
Force can be calculated from the expression for potential energy, which is a function of position. The component of a conservative force, in a particular direction, equals the negative of the derivative of the corresponding potential energy with respect to the displacement in that direction. For regions where potential energy changes rapidly with displacement, the work done and force is maximum. Also, when force is applied along the positive coordinate axis, the potential energy decreases with...
01:25Poisson's And Laplace's Equation
The electric potential of the system can be calculated by relating it to the electric charge densities that give rise to the electric potential. The differential form of Gauss's law expresses the electric field's divergence in terms of the electric charge density.
01:07Diffusion on Chromatography Columns
In column chromatography, when an analyte is introduced as a narrow band at the top of the column, the solutes begin to separate and broaden, developing a Gaussian profile. This broadening occurs due to various factors, such as longitudinal diffusion.
Longitudinal diffusion occurs when the solute molecules in the mobile phase diffuse from the more concentrated center of the chromatographic band to the more dilute regions on either side, both towards and against the flow direction. This...
Longitudinal diffusion occurs when the solute molecules in the mobile phase diffuse from the more concentrated center of the chromatographic band to the more dilute regions on either side, both towards and against the flow direction. This...
01:28Debye–Huckel–Onsager Conductance Equation
The Debye-Hückel-Onsager equation is a cornerstone of physical chemistry, providing a method to determine the molar conductance (Λm) and molar conductance at infinite dilution (Λ°m) for uni-univalent electrolytes.Uni-univalent electrolytes are electrolytes that dissociate in solution to produce one cation with a +1 charge and one anion with a –1 charge per formula unit.This equation addresses two crucial phenomena: the asymmetry effect and the electrophoretic effect. According to this equation,...
01:17Passive Diffusion: Overview and Kinetics
Passive diffusion is a critical process that allows small lipophilic drugs to cross the cell membrane along a concentration gradient. This mechanism's efficiency depends on four primary factors: the membrane's surface area, the drug's lipid-water partition coefficient, the concentration gradient, and the membrane's thickness.
When administered orally, drugs establish a substantial concentration gradient between the gastrointestinal (GI) lumen and the bloodstream, expediting their diffusion into...
When administered orally, drugs establish a substantial concentration gradient between the gastrointestinal (GI) lumen and the bloodstream, expediting their diffusion into...