Permeameter wall effect

Abstract

If the resistance to flow through a granular medium is to be measured in the laboratory with a permeameter, care must be exercised in interpreting the results so as to account for wall effect, A cursory analysis presented in this paper indicates that in general the ratio of permeameter diameter to mean particle diameter should exceed about 40 to eliminate any sizeable effect of the container wall. For ratios less than 40 the Reynolds number of the flow has great influence on wall effect.

Developing your own automated leaching column system for studying solute transport in clay soil

“…The signal from the analytic device may then be transferred to a signal processor for storage and further data analysis. Other types of burettes or non-adsorbing cylinders can be used as column as long as the ratio of insider diameter of column to the mean diameter of the soil particles is greater than 40 to minimize the wall effect [1]. Several pumps could be used besides the peristaltic pump, including, for example, a multichannel syringe pump [10], or a peristaltic pump from an auto-analyzer.…”

“…Apparatus induced dispersion can be minimized with a large ratio (>40) of column inside diameter to mean particle diameter of the media [1] and a slightly negative head [2]. For studies with soil materials, the ratio should not be a problem if the column inside diameter is greater than 2 cm because the mean diameter of particles of most soils are less than 0.5 mm.…”

“…In addition, the BTC can be influenced by hydraulic parameters, such as flux or fluid velocity, and dispersion induced by the apparatus, which mainly consists of the wall effect [1] and the porous plate effect [2] and varies with column design.…”

“…Most systems to date have been used with granular particles, such as lead shot [1] or glass beads [2], and sandy, loam or aggregated soils [4,7]. There seems lack of application of the existed systems to clay soils which frequently have low A commercially available column leaching apparatus has been used for the determination of solute dispersion coefficients [11].…”

Correction Method for Hydraulic Conductivity Measurements Made Using a Fixed Wall Permeameter

“…Concerning a fixed wall cell, the boundary effect has long been investigated. Franzini [11] demonstrated that the porosity in the vicinity of sidewall is greater than within the bed packed with grains because the grains close to the wall cannot be packed as tightly as those inside soil bed. e bed can be divided into two zones, namely, the outer shell near the wall and the core whose porosity is free from the boundary effect.…”