Determination of the air entry value and bubbling value of a ceramic cup based on two-phase flow mechanism in porous media

Tensiometer has been widely used in measurements of soil moisture potential although no simple and easy methodology is available to determine its applicability range.A series experiments were conducted to determine the hydraulic conductivity,air entry value,and bubble point via the two setups for conductivity,air entry value and bubble point determination,respectively.The results show that(1) the air entry value is subject to the influence of saturation history and the determination procedures is not repeatable,while the bubble point is of good repeatability and is immune to saturation history.(2) A certain pertinence exists between the air entry vale and the bubble point,thus,the bubble point can give a rough and sound estimation of the air entry value by multiple 0.25,which provides a simplified procedure to determine the application range of a tensiometer.(3) The drainage procedure of a ceramic cup is successfully interpreted by a conceptual model of adsorption-seepage water and radius-varied capillary bundle model,and the drainage model for porous media was proposed based on two-phase flow mechanism.