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The presence of tall buildings in cities affects momentum and scalar exchange within and above the urban canopy. As wake effects can be important over large distances, they are crucial for urban-flow modelling on and across different spatial scales. We explore the aerodynamic effects of tall buildings on the microscale to local scales with a focus on the interaction between the wake structure, canopy and roughness sublayer flow of the surroundings in a realistic urban setting in central London. Flow experiments in a boundary-layer wind tunnel use a 1:200 scale model with two tall buildings (81 m and 134.3 m) for two wind directions. Large changes in mean flow, turbulence statistics and instantaneous flow structure of the wake are evident when tall buildings are part of the complex urban canopy rather than isolated. In the near-wake, the presence of lower buildings displaces the core of the recirculation zone upwards, thereby reducing the vertical depth over which flow reversal occurs. This amplifies vertical shear at the rooftop and enhances turbulent momentum exchange. In the near part of the main wake, lateral velocity fluctuations and hence turbulence kinetic energy are reduced compared to the isolated building case as eddies generated in the urban canopy and roughness sublayer distribute energy down to smaller scales that dissipate more rapidly. Evaluation of a wake model for flow past isolated buildings suggests model refinements are needed to account for such flow-structure changes in tall-building canopies. [ABSTRACT FROM AUTHOR]

The benchmarking optimization of a wind farm layout was applied to the offshore wind farm on Jeju Island, Korea. This work focused on optimizing not only the annual energy production (AEP), but also the electrical grid cost and foundation cost. The benchmark wind farm will be installed on the west coast of Jeju. Ten turbines will be constructed in a simple straight line. To predict the aerodynamic loadings of the wind turbines, the Larsen model was used in combination with the unsteady vortex lattice method. The cost models developed by Larsen were used. In order to optimize the wind farm layout, the total optimization framework developed by the Technical University of Denmark, TOPFARM, was used. The results showed that the objective function values, which included the AEP and cost models, were increased, and an irregular layout was produced compared to the baseline layout. [ABSTRACT FROM AUTHOR]