MS-Micro 4: Improved treatment of roughness variations.

1. MS-Micro 4: Improved treatment of roughness variations. Wensong Weng a, Peter A Taylor a,b, Jim Salmon b a Department of Earth and Space Science and Engineering, York University, 4700 KeeleStreet, Toronto, Ontario, Canada M3J 1P3 b Zephyr North Canada Ltd, 850 Legion Road Unit 20, Burlington, Ontario, Canada L7S 1T5 Based on the 1-D planetary boundary layer model of Weng and Taylor (2003) with E-ℓ turbulence closure, 2-D (Weng et al, 2009) and 3-D numerical models are developed to study the atmospheric boundary-layer flow over single or multiple changes in surface conditions as well as general spatial distributions. Topographic effects are estimated using the MSFD model and the perturbations caused by roughness and topography are linearly superimposed. Effects of thermal stability can also be included. Sample results for winds blowing off-shore over lake Ontario (a possible offshore wind farm site) are shown in Figure 1 (no topography). Offshore flow: from Toronto over Lake Ontario? Neutral stratification. Note increase at 80m requires fetch > 1 km Bolund (from the Risö web site) BOLUND results with an MS-Micro 4 prototype The results submitted were from the combination of a) a 2-D NLMSFD model and a 2-D roughness change model; b) a 3-D MSFD model and a 3-D roughness change model. Results with the 3-D roughness (only) model are also shown below, for Case 1. Input z0 field Contour plot of fractional speed-up caused by roughness variations at z = 2 m above ground Along the line y = 0. References: Weng, W. and Taylor, P.A., 2003: On modelling the one-dimensional atmospheric boundary layer. Boundary-Layer Meteorol. 43, 273-286. Weng, W., Taylor, P.A. and Salmon, J.R., 2009: A 2-D numerical model of boundary-layer flow over single and multiple surface condition changes. J. Wind Eng. Ind. Aerodyn. (2009), doi:10.1016/j.jweia.2009.10.006