Effect of electromagnetic stimulation on hydraulic conductivity

Hydraulic conductivity is a measure of the rate at which water flows through porous media. In this study, the effect of radiofrequency (RF) waves on hydraulic conductivity was investigated. Bentonite clay was tested in rigid-wall, cylindrical permeameters and stimulated using monopole antenna. Falling-head tests were performed to measure the hydraulic conductivity of the clay and sand samples, respectively. Using RF frequencies of 80, 94 and 153MHz, flow through the clay sample was sharply decreased for a relatively short period of time and then stabilised at a higher hydraulic conductivity. The test was replicated with a decrease of the input RF power from 30 to 20W, and then to 10 W. The results revealed that the change in the hydraulic conductivity was larger at the higher input RF power. Measurements of the electric field component of RF waves were performed to map the electric field. In addition, the electric field was simulated using COMSOL Multiphysics for better three-dimensional visualisation and analysis. The possibility of a dielectrophoretic phenomenon governing this effect was studied for the simulated data. The result was in agreement with the results from the experimental field investigation.