Preprints
https://doi.org/10.5194/wes-2019-68
https://doi.org/10.5194/wes-2019-68
30 Sep 2019
 | 30 Sep 2019
Status: this preprint was under review for the journal WES but the revision was not accepted.

The impact of a forest parametrization on coupled WRF-CFD simulations during the passage of a cold front over the WINSENT test-site

Daniel Leukauf, Asmae El-Bahlouli, Kjell zum Berge, Martin Schön, Hermann Knaus, and Jens Bange

Abstract. The Weather Research and Forecasting (WRF) Model has been coupled with a URANS Model to simulate the passage of a cold front over the WINSENT site, a wind energy test-site under development. It is located on a hill near a steep, forested terrain edge. A high spatial resolution is necessary to simulate the flow over this complex site accurately for which reason the WRF model is run at high resolution in LES mode coupled to a URANS model with an even higher resolution. A forest parametrization is implemented in both models to account for the drag caused by the trees. The main result is that the WRF model without forest parametrization overestimates the wind speed in the lowest 100 m above ground on average by about 3 ms−1. Introducing the forest parametrization reduces the bias considerably, but overcompensates the error at 45 m above ground, leading to a small negative bias. The URANS model further improves the flow simulation and provides a nearly bias free simulation compared to observation. Observations are taken with a 100-m high met-mast at five different levels. In addition, wind measurements taken with an Unmanned Aircraft System provide data along a cross-section that intersects the terrain edge.

Daniel Leukauf, Asmae El-Bahlouli, Kjell zum Berge, Martin Schön, Hermann Knaus, and Jens Bange
 
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Daniel Leukauf, Asmae El-Bahlouli, Kjell zum Berge, Martin Schön, Hermann Knaus, and Jens Bange
Daniel Leukauf, Asmae El-Bahlouli, Kjell zum Berge, Martin Schön, Hermann Knaus, and Jens Bange

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Latest update: 19 Apr 2024
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Short summary
Hilltops are in principle favorable locations for wind turbines due to the increased mean wind speed that can be found over hills. However, the more complex terrain leads to more complex flow conditions and increased turbulence. Numerical simulations are required to understand the flow conditions at sites in hilly terrain. A numerical simulation of the passage of a cold front over the site shows that increased drag caused by the nearby forests must be included in the model.
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