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EFFECTS OF ELECTROOSMOSIS ON SOIL TEMPERATURE AND HYDRAULIC HEAD: II. NUMERICAL SIMULATION
Citation:
Chen, J. L., S R. AlAbed*, J A. Ryan*, M H. Roulier*, AND M Kemper*. EFFECTS OF ELECTROOSMOSIS ON SOIL TEMPERATURE AND HYDRAULIC HEAD: II. NUMERICAL SIMULATION. JOURNAL OF ENVIRONMENTAL ENGINEERING 128(7):596-603, (2002).
Description:
A numerical model to simulate the distributions of voltage, soil temperature, and hydraulic head during the field test of electroosmosis was developed. The two-dimensional governing equations for the distributions of voltage, soil temperature, and hydraulic head within a cylindrical domain are derived based on the principles of charge, energy, and mass conservations, Darcy's law, Ohm's law, and Fourier's law of heat conduction. We assumed that the voltage distribution was at steady state, whereas soil temperature and hydraulic head were at transient state during the test. The simulated domain was segmented with a nod-centered finite-difference scheme and the resulting equations were solved numerically with the Successive Over Relaxation method. The parameters (such as electrical, thermal, hydraulic, and electroosmotic properties of the soil, graphite, and sand) that were required by the model were measured either using core samples or slug tests. The voltage distribution from the model is able to predict the pattern as well as the magnitude of the observed profiles. The simulated temperatures are similar in pattern and are within 3C of the observed values in the four casings during four weeks of electroosmosis. The rates of temperature changes with increasing energy input predicted by the model are in agreement with the observed changes. The output from the hydraulic head simulations showed that the model could predict the patterns of hydraulic head changes in the vicinities of the mesh and graphite electrodes. The model, however, underestimated the magnitude of the changes close to the anode. The simulated electroosmotic flow rate of 0.9 L/hr is also consistent with the observation of 0.6 to 0.8 L/hr.