ECN publication
Large off-shore windfarms : linking wake models with atmospheric boundary layer models
Schepers, J.G.; Barthelmie, R.; Kostas, K.; Lange, B.; Schlez, W.
Published by: Publication date:
ECN Wind Energy 1-3-2002
ECN report number: Document type:
ECN-RX--02-007 Conference Paper
Number of pages: Full text:
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Presented at: Off-shore wakes, measurements and modelling, Roskilde, Denmark, 7-8 maart 2002.

One of the main objectives of the EU-5th Framework project ENDOW (EfficientDevelopment of Off-Shore Wind Farms) is to develop a design tool, which calculates the power production of a large off-shore wind farm. This design tool will consist of an atmospheric model coupled with a wake model. An atmospheric model is meant to calculate the free flow in off-shore conditions, taking into account terrain and meteorological effects, but usually no wind turbines and resulting wake effects are included. The wake model is then meant to fill this gap, i.e it calculates the disturbance from a wind turbine on the initial flow, where meteorological and terrain effects are usually not included in the principal wake calculations. Some wake models assume that the outer atmospheric flow remains constant over the farm and as a consequence the flow at infinity returns to the initial flow field again. Other wake models calculate a wake deficit under the assumption of a constant outer flow, and superimpose this wake deficit on a (possibly) varying outer flow. Within the ENDOW project various candidate atmospheric and wake models are available to be incorporated into the design tool. In order to gain insight into the suitability of the various models and in the way how they can be linked, a questionnaire has been distributed between the various modelling partners. Using the response on the questionnaire an inventory of the different models has been made with emphasis on the items which determine the compatibility of the different models. Aspects, which are of importance for this compatibility are consistancy from a physical point of view, but also consistancy from an informatic point of view (i.e. input/output, platform, compiler etc.). In the paper the first results from the questionnaire are summarized. Thereto Section 2 gives a brief description of the questionnaire. This is followed by section 3 and 4, in which the response on the wake and the atmospherice models is summarized. In section 5 some first ideas on the interfacing are proposed. It must be noted that the present inventory is very preliminary: Many answers on the questionnaire are still lacking and the paper is mainly intended to serve as food for discussion within the project group.

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