2024 Volume 80 Issue 15 Article ID: 23-15040
In risk assessments of slopes after rainfall, to quantify the amount of fluid outflow from the system, obtaining the amount of evaporation is essential, which is ground surface moisture flux boundary conditions. This paper focuses on the bulk method to estimate evaporation and discusses the calculation method of evaporation efficiency, an essential parameter of the bulk method, under natural convection. Firstly, the exchange speed necessary for calculating the evaporation efficiency is examined from thermodynamics, and the calculation method considering the difference in heat capacity between soil and water is proposed. Secondly, from the laboratory experiments, evaporation efficiency is calculated using the exchange speed based on the above-proposed method, and its validity and applicability are evaluated. As a result, it was confirmed that the evaporation efficiency can be calculated as below 1, which satisfies the variational range by using the proposed method. In addition, a method for organizing the data to eliminate the influence of the initial conditions of the laboratory experiments on the evaporation efficiency is presented.
