Two-layer integral model for calculating the evaporation rate from a liquid surface

摘要

An integral model is presented for predicting the evaporation rate from a single component liquid layer exposed to wind. This approach simplifies the solution of the convection-diffusion equation by averaging over the height of the concentration boundary-layer thickness. The model is valid for hydraulically smooth as well as rough surfaces and yields results which are in good agreement with those obtained by mathematically more rigorous methods. The new integral model is conceptually simpler and provides and explicit estimate of the concentration boundary-layer thickness. It allows a compact analytic solution for the evaporation rate with emphasis on the diffusion process in the laminar sublayer, accounted for by means of empirical wall functions.