Related Experiment Video
Updated: May 18, 2026
12:32
Combining Fluidic Devices with Microscopy and Flow Cytometry to Study Microbial Transport in Porous Media Across Spatial Scales
Published on: November 25, 2020
Comment on "Frequency-dependent dispersion in porous media"
1Mathematical Institute, University of Oxford, 24-29 St Giles', Oxford OX1 3LB, UK.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|September 26, 2012
Summary
The frequency-dependent dispersion tensor for porous media transport is corrected, revealing it does not depend on process frequency. This spectral analysis clarifies solute transport descriptions in porous media.
Area of Science:
- Geophysics and Environmental Science
- Fluid Dynamics in Porous Media
- Solute Transport Modeling
Background:
- The study addresses the "frequency-dependent" dispersion tensor derived by Valdès-Parada and Alvarez-Ramirez for solute transport in porous media.
- This tensor aimed to describe transport under periodic processes using volume averaging.
Discussion:
- The derived dispersion tensor D(γ)(*) definition is shown to be erroneous.
- A corrected version, D(γ)(*c), is presented, establishing equivalence with Moyne's prior work.
- The term "frequency-dependent dispersion" is identified as misleading, as the tensor is independent of process frequency.
Key Insights:
- The corrected dispersion tensor D(γ)(*c) provides a more accurate description of solute transport.
- The analysis reveals that the tensor's behavior relates to spectral analysis of relaxation to a steady-state, not periodic excitation.
- This work clarifies the physical interpretation of dispersion in porous media.
Outlook:
- Further research can explore the implications of this corrected tensor for various porous media flow scenarios.
- This clarification aids in developing more robust models for contaminant transport and subsurface hydrology.
- The findings contribute to a deeper understanding of solute dynamics in complex geological formations.
Related Concept Videos
00:54Distribution and Dispersion
To understand intra-specific interactions in populations, scientists measure the spatial arrangement of species individuals. This geographic arrangement is known as the species distribution or dispersion. Highly territorial species exhibit a uniform distribution pattern, in which individuals are spaced at relatively equal distances from one another. Species that are highly tied to particular resources, such as food or shelter, tend to concentrate around those resources, and thus exhibit a...
01:21Frequency-dependent Selection
When the fitness of a trait is influenced by how common it is (i.e., its frequency) relative to different traits within a population, this is referred to as frequency-dependent selection. Frequency-dependent selection may occur between species or within a single species. This type of selection can either be positive—with more common phenotypes having higher fitness—or negative, with rarer phenotypes conferring increased fitness.
01:07Propagation of Waves
When a wave propagates from one medium to another, part of it may get reflected in the first medium, and part of it may get transmitted to the second medium. In such a case, the interface of the two mediums can be considered as a boundary that is neither fixed nor free.
Consider a scenario where a wave propagates from a string of low linear mass density to a string of high linear mass density. In such a case, the reflected wave is out of phase with respect to the incident wave, however the...
Consider a scenario where a wave propagates from a string of low linear mass density to a string of high linear mass density. In such a case, the reflected wave is out of phase with respect to the incident wave, however the...
01:25Permeability of Concrete
Permeability in the context of concrete refers to how easily liquids or gases can pass through the material. This quality is crucial for assessing the water-tightness and durability of concrete structures and their resistance to chemical attacks. Concrete permeability can be determined through comparative laboratory tests. These tests typically involve sealing a concrete specimen from the sides, applying water pressure to the top surface with pressure, and measuring the amount of water passing...
01:20Porosity and Absorption of Aggregate
Aggregates contain pores of varying sizes; while some are completely enclosed within the particles, others open onto the surface, allowing water to penetrate. The porosity of aggregates is a major factor contributing to the overall porosity of concrete, given that aggregates constitute about three-quarters of concrete's volume.
When all pores in an aggregate are filled with water, the aggregate is considered saturated and surface-dry. If left in dry air, water will evaporate until the aggregate...
When all pores in an aggregate are filled with water, the aggregate is considered saturated and surface-dry. If left in dry air, water will evaporate until the aggregate...
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...