Evaporation front and its motion

Jiří Mls

doi:10.5194/hess-26-397-2022

Abstract

Abstract. The evaporation demands upon a rock or soil surface can exceed the ability of the profile to bring a sufficient amount of liquid water. A dry surface layer arises in the porous medium that enables just water vapor flow to the surface. The interface between the dry and wet parts of the profile is known as the evaporation front. The paper gives the exact definition of the evaporation front and studies its motion. A set of differential equations governing the front motion in space is formulated. Making use of a set of measured and chosen values, a problem is formulated that illustrates the obtained theory. The problem is solved numerically, and the results are presented and discussed.

Highlights

Under arid or semiarid conditions, evaporation demands usually exceed the ability of an exposed porous medium to provide liquid-phase water
The phenomenon is preconditioned by the fact that the porous medium becomes impervious to the liquid-phase water if the water content becomes sufficiently small
Denote by, ⊂ R3 the domain in space and by (0, T ) the time interval in which we study the transport process and suppose that the movable liquid-phase water occupies an open part Gw of the time–space domain G, where

Summary

Introduction

Under arid or semiarid conditions, evaporation demands usually exceed the ability of an exposed porous medium to provide liquid-phase water. Il’ichev and Shargatov (2013) started their study with similar assumptions concerning the governing laws and investigated the resulting transition surfaces and conditions of loss of their stability Unlike these studies, the present paper aims to define the evaporation front by means of porous-medium characteristics and to formulate the law of its motion generally not involving any particular law governing the water transport. The present paper aims to define the evaporation front by means of porous-medium characteristics and to formulate the law of its motion generally not involving any particular law governing the water transport This approach makes it possible to use any set of flow and transport laws when formulating a problem of the evaporation front motion. The goal of this paper is to give an exact definition of the evaporation front and to formulate the law of its motion

Basic assumptions and theory

Problem formulation

One-dimensional problem

A solved problem

Discussion and conclusions