Unsteady numerical simulation and data analysis of hysteresis associated with water uptake in capillary tube

Capillary action and water uptake are tremendously fundamental and practical phenomena which used in a wide range of applications from industries and medical to agricultural fields. This work aims to provide a detailed numerical investigation and statistical data sampling of capillary action and water uptake, considering hysteresis associated with density, surface tension, contact angle, gravity force, tube diameter, and inclination angle effects. The main selected domain is ۱mm and ۵mm in diameter and height. The solver type is chosen as a pressure-based solver, and time-dependent data sampling is utilized. The flow field is selected as incompressible, constant properties, Newtonian homogeneous fluid. The finite volume method on a co-located grid system is used. The code uses algebraic multigrid schemes to accelerate the solution. The message passing interface parallelized code is used. The bisection algorithms are used for partitioning. The pressure and velocity fields were coupled using the PISO algorithm. The results show that increasing capillary tube diameter or surface tension enhances uptake velocity by ۹۸–۱۰۰% and reduces filling time by ۴۹–۵۰%, respectively, though inertial/dissipative effects caused minor deviations (۱–۱۲%) in surface tension cases. Flow velocity scaled linearly with contact angle doubling filling time, while gravitational acceleration induced only marginal delays with negligible meniscus impact, supporting its omission in engineering models. Transient meniscus asymmetry occurred in inclined tubes (۴۵°) due to contact angle disparity between halves, yet filling duration remained identical to vertical and horizontal orientations despite geometric differences in meniscus evolution.

کلیدواژه ها:

Numerical Modeling ، Capillary Action ، Statistical Data Sampling ، Fluid Dynamics