文档介绍：? A 2-D numerical model is developed to study atmospheric boundary-layer flow over single or multiple changes in surface conditions. These changes include surface roughness, thermal and moisture properties. ? A simple, analytic model dealing with the surface roughness change effects in neutral stratification has also been developed using the concept of an Internal Boundary Layer. ? Model results are discussed pared with other approaches and with published field data. ? Impacts of roughness changes on wind energy potential and siting issues will be discussed. ? Financial support for York University participants in this work has been provided by CFCAS and MITACS Internal Boundary Layers InternalBoundaryLayer EquilibriumLayer TransitionLayer zx ?0WatersurfaceLandsurface Unmodifiedflow Wind From poster by Hong Liu Idealized velocity profiles – based on modelling and observation: Single roughness change, surface layer (logarithmic profile) z 01z 02? 1? 2? ln(z)Uz 02z 01? 1? 2? ln(z)U a)Smooth-roughtransitionb)Rough-smoothtransition GLW – Guidelines for Windows. GLW – simple roughness change Upstream + Reference z 0 = Downstream z 0 = Prediction site is 2 km from roughness change. GLW includes topographic speed-up Now developed for multiple roughness changes Longer fetches, greater heights. PBL model, neutral or stratified With Boundary-layer approximations, and in 2D, we solve the RANS and Continuity equations, together with closure hypotheses for Reynolds stresses and fluxes. Details in Weng et al. – subm to JWEIA z wq z QWx QU z wz Wx U z vw UUfz VWx VU z uw VVfz UWx UU g g?????????????????????????????????????????????????)( )(????0 )( Pr ,, ,, 2/3 2/1 2/1????????????????????????????????????????????????????????????????z Wx U z EKz Ewgz V vw z Uuw z EWx EU , EK, EK z QK wq z Kw z VK vw z UKuw m d mh mm h h m m????????? Closure hypotheses, TKE and length scale equations ???? 0 )( Pr ,, ,, 2/3 2/12/1???????????????????????????????????