Stability classification for CFD simulations in complex terrain. Dr. Carolin Schmitt a Dr. Cathérine Mei β ner b Andrea Vignaroli b a juwi Wind GmbH, Energie-Allee 1, 55286 Wörrstadt, Germany b WindSim AS, Fjordgaten 15, N-3125 Tønsberg, Norway.
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Stability classification for CFD simulations
in complex terrain
Dr. Carolin Schmitta
Dr. Cathérine Meiβnerb
ajuwi Wind GmbH, Energie-Allee 1, 55286 Wörrstadt, Germany
b WindSim AS, Fjordgaten 15, N-3125 Tønsberg, Norway
EWEA 2013 Annual Event, 4-7th February 2013, Vienna
Simulations don’t fit measurements
Streamlines in CFD Modelling
Vertical Speed in CFD Modelling
Model Data Possibilities:
MERRA data is free available in the internet. MOL can be calculated by the variables given in the data set.
Modern-ERA Retrospective Analysis for Research and Applications, http://gmao.gsfc.nasa.gov/merra/)
The question is which of the four surrounding MERRA data points should be used to assess the stability parameters or if an inverse distance weighting can be used.
EWC Wind Potential Analysis provide downscaled MERRA data with auxiliary information.
All sites with one or more met towers, A and B with additional Lidar measurements
Around 10% fewer stable cases in MERRA
Good correlation of speed and temperature data but not for wind direction
Main stable directions SE/NW not enough represented in MERRA
Good agreement Mast Gradient and MERRA Gradient/MOL
MERRA gives more instable cases and fewer neutral ones, stable distribution ok.
Too much instable cases and around 10% fewer stable cases. Site generally shows more neutral stratification.
Influence of land/sea surface distribution can influence the quality of diurnal temperature cycle in MERRA in comparison to only land surface.
More instable cases are produced
Stability values and distribution (sectorwise) can be used to CFD model setup
MERRA dataisfreeavailable in theinternet.
The MOL is not givendirectly but canbecalculatedbythe variables given in thedataset.
g = Gravity
cpl/cp = heatcapacity (dry/wet)
Tv = virtualtemperature
tt = temperature
spfh = specifichumidity
shtfl = surfaceheatflux
lml = lowestmodellevel
The questioniswhichofthefoursuroundingMerradatapointsshouldbeusedtoassessthestabilityorif an inverse distanceweightingcanbeused.