Effect of pore structure on capillary condensation in a porous medium

The Kelvin equation relates the equilibrium vapor pressure of a fluid to the curvature of the fluid-vapor interface and predicts that vapor condensation will occur in pores or irregularities that are sufficiently small. Past analyses of capillary condensation in porous systems with fractal structure have related the phenomenon to the fractal dimension of the pore volume distribution. Recent work, however, suggests that porous systems can exhibit distinct fractal dimensions that are characteristic of both their pore volume and the surfaces of the pores themselves. We show that both fractal dimensions have an effect on the thermodynamics that governs capillary condensation and that previous analyses can be obtained as limiting cases of a more general formulation.Mechanical Engineerin

Approximate analytical solution of the Boussinesq equation

A new approximate solution of the one-dimensional Boussinesq equation is presented for a semi-infinite aquifer when the hydraulic head at the source is an arbitrary function of time. Estimates for recharge, discharge, and elevation of the water table are given. The simplicity and accuracy of the approximation are compared with 'exact' numerical and analytical solutions. The method of solution is illustrated with several examples including the commonly treated case of a constant boundary head and a nonmonotonically varying boundary head

Infiltration in soils with a saturated surface

Key Points Analytic description of infiltration in soils Comparison of constant flux and saturated surface infiltration Linking infiltration to soil/water properties An earlier infiltration equation relied on curve fitting of infiltration data for the determination of one of the parameters, which limits its usefulness in practice. This handicap is removed here, and the parameter is now evaluated by linking it directly to soil-water properties. The new predictions of infiltration using this evaluation are quite accurate. Positions and shapes of soil-water profiles are also examined in detail and found to be predicted analytically with great precision