Title

Session 4 - Block-effective dispersivity in heterogeneous media: Effects of porosity and distribution coefficient variability

Presenters

Farang Botros

Location

University of Nevada Las Vegas, Stan Fulton Building

Start Date

1-6-2007 1:55 PM

End Date

1-6-2007 2:02 PM

Description

The concept of block-effective dispersivity represents the difference between the classic macrodispersivity values and the dispersivity captured by the numerical grid. We use Monte Carlo simulations of flow and transport in two-dimensional random conductivity, porosity, and distribution coefficient fields to explore the influence of spatial variability on the block-effective dispersivity. Different correlation structures between porosity, distribution coefficient, and hydraulic conductivity are assumed; positive correlation, negative correlation, and no-correlation using random fields with exponential covariance. Different grid sizes are also simulated from very fine grids (grid-cell size is smaller than the correlation length) to coarse grid (grid-cell size is larger than the correlation length). Results suggest that it is important to examine the role of distribution coefficient and/or porosity variability, and the possible correlation between them in calculating block-effective dispersivity. When porosity and/or distribution coefficient is positively correlated with conductivity, block-effective longitudinal dispersivity is smaller than the case of random conductivity with constant variables while the block-effective transverse dispersivity is larger than the case of constant variables. The negative correlation case leads to the opposite results. When porosity and/or distribution coefficient is spatially variable but uncorrelated to the hydraulic conductivity, block-effective macrodispersivity is slightly different than the case of constant variables.

Keywords

Block-effective dispersivity; Hydraulic conductivity; Materials -- Properties; Materials science; Permeability; Porosity; Porosity variability

Disciplines

Materials Science and Engineering

Language

English

Permissions

Use Find in Your Library, contact the author, or use interlibrary loan to garner a copy of the article. Publisher copyright policy allows author to archive post-print (author’s final manuscript). When post-print is available or publisher policy changes, the article will be deposited


Share

COinS
 
Jun 1st, 1:55 PM Jun 1st, 2:02 PM

Session 4 - Block-effective dispersivity in heterogeneous media: Effects of porosity and distribution coefficient variability

University of Nevada Las Vegas, Stan Fulton Building

The concept of block-effective dispersivity represents the difference between the classic macrodispersivity values and the dispersivity captured by the numerical grid. We use Monte Carlo simulations of flow and transport in two-dimensional random conductivity, porosity, and distribution coefficient fields to explore the influence of spatial variability on the block-effective dispersivity. Different correlation structures between porosity, distribution coefficient, and hydraulic conductivity are assumed; positive correlation, negative correlation, and no-correlation using random fields with exponential covariance. Different grid sizes are also simulated from very fine grids (grid-cell size is smaller than the correlation length) to coarse grid (grid-cell size is larger than the correlation length). Results suggest that it is important to examine the role of distribution coefficient and/or porosity variability, and the possible correlation between them in calculating block-effective dispersivity. When porosity and/or distribution coefficient is positively correlated with conductivity, block-effective longitudinal dispersivity is smaller than the case of random conductivity with constant variables while the block-effective transverse dispersivity is larger than the case of constant variables. The negative correlation case leads to the opposite results. When porosity and/or distribution coefficient is spatially variable but uncorrelated to the hydraulic conductivity, block-effective macrodispersivity is slightly different than the case of constant variables.