Objective Method for Estimating Surface Roughness Length for

this paper was to develop and test three objective, reproducible, analytical methods for estimating surface roughness as a function of wind direction at refineries (or other areas of interest). The estimation techniques use physical dimensions and spacings of the structures at refineries or other built up sites and are referred to as the Lettau , Counihan and Simplified Counihan methods. The three methods are statistically evaluated in this paper by comparing their predictions against surface roughness length estimates obtained from wind speed measurements over scale models of three refineries and two uniform roughness configurations. The Lettau method has been verified against field observations for a homogeneous roughness configuration; however, Wieringa concludes that the Lettau method is limited to moderately inhomogeneous situations. The Counihan methods have only been tested against homogeneous roughness configurations in a wind tunnel. This paper will show whether the methods can be extended to moderately inhomogeneous situations like a refinery based measurements in scale model refineries. The paper also discusses the future validation of the wind tunnel results through an upcoming field evaluatio