Transport of sessile droplet in porous medium with evaporation and chemical reaction

Abstract

The dynamic of a sessile droplet spread of a wetting Newtonian fluid into a porous substrate in the presence of evaporation and chemical reaction is considered. The function for capillary pressure is found to be different from the classic Leverett-udell function. The evaporation and chemical reaction are fully coupled with the porous media flow with impact on the continuity, momentum, and energy equations. The multiphase and multi-component Navier-Stokes equations for sessile droplets in a porous medium going through phase change and chemical reaction are solved explicitly on a finite difference mesh and the results are validated with laboratory and open air experimental data. The Runge-Kutta fourth order method is used to integrate the governing equations in time. In the model, chemical reactions are allowed among all phases; solid, liquid, and vapor. The local properties are functions of the species or phases that are present therefore, varying in time. Pesticides and any chemical that is released into the environment can evaporate and may also enter a chemical reaction with other pre-existing chemicals or simply moisture in the environmental substrates. The technique is proven to be very accurate and robust with widespread applications in defense, environmental safety, pharmaceuticals, and medical fields.