Analysis of Evaporation Data under Roughness-Induced Wind Flow

Abstract

Roughness-induced wind flow is commonly encountered around water bodies. It is well known that wind velocity enhances evaporation. However, the way this enhancement takes place in roughness-induced flow has been less explored. In this paper, a set of 200 data of an experimental investigation of the evaporation rates of water under forced convection conditions created by roughness elements from a circular pan fitted in the bottom wall of a wind tunnel test section are analyzed. The range of parameters used in this work are as follows: pan water temperature 30–50°C, wind velocity 4.68–17.52 m/s, and relative roughness height 0.011–0.075. Evaporation rates are related as a function of the vapor pressure differential, wind velocity, and relative roughness height of the obstructions introduced in the upstream of the air flow. It is found that evaporation rates are a nonlinear function of the relative roughness height, and evaporation estimates can contain a large error if such roughness-induced effects are neglected.