Memory Requirements for full-field wind arrays

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Marshall.Buhl
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Memory Requirements for full-field wind arrays

Postby Marshall.Buhl » Wed Jul 25, 2012 11:10 am

The formulas I use to determine the cumulative size of the bigger arrays in TurbSim is:

Code: Select all

EffSimLen = FASTsimulationTime + GridWidth/MeanWindSpeed (the last term will not be used in a future version of TurbSim)
NumTimeSteps = EffSimLen/TimeStep + 1
SpectralGridElements = (NYGrids*NZGrids)^2
SpectralMatrixElements= 3*NZgrids*NumTimeSteps
ComponentElements= SpectralMatrixElements*NYGrids
TotalElements = SpectralGridElements + SpectralMatrixElements + 2*(ComponentElements + NZGrids) + NYGrids

BytesRequired =  4*TotalElements     (if using single precision, the TurbSim default)
GBytesRequired = BytesRequired/(1024)^3

If you are running a sweep of wind speeds and want to determine the worst case, the lowest wind speed you run will produce the most time steps and consume the most memory when running TurbSim. When we modify TurbSim and InflowWind (used by FAST) to cycle through 10-minute data, the wind speed won't matter as we will no longer add extra data at the beginning and end of the file to accommodate analysis nodes upwind and downwind of the tower.

The size of the turbulence array read into InflowWind is:

Code: Select all

FFArrayElements = 3*NZGrids*NYGrids*NumTimeSteps

The formula for bytes and GBs is left as an exercise for the student. :P
Mr. Marshall L. Buhl Jr.
NWTC-3811
National Renewable Energy Laboratory
Golden, CO 80401 USA
Marshall.Buhl@nrel.gov
Voice: +1 (303) 384-6914
Cell: +1 (303) 915-6623
Fax: +1 (303) 384-7079

Bonnie.Jonkman
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Re: Memory Requirements for full-field wind arrays

Postby Bonnie.Jonkman » Wed Jul 25, 2012 12:05 pm

If you don't want to do all the calculations Marshall took the time to explain, you can use this Excel file to approximate the size of files generated by TurbSim v1.50: http://wind.nrel.gov/public/bjonkman/De ... Sizes.xlsx
Bonnie Jonkman

Envision Energy USA, 2016-
National Renewable Energy Laboratory, 2003-2016

Trevor.Demme
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Re: Memory Requirements for full-field wind arrays

Postby Trevor.Demme » Tue Jan 14, 2014 1:06 pm

Bonnie, that is a life saving spreadsheet you shared there. I was not looking forward to calculating the file sizes at all. Many thanks!
Last edited by Trevor.Demme on Sun Oct 18, 2015 7:06 am, edited 1 time in total.

Bonnie.Jonkman
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Joined: Thu Nov 10, 2005 10:51 am
Organization: Envision Energy USA
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Re: Memory Requirements for full-field wind arrays

Postby Bonnie.Jonkman » Thu Feb 06, 2014 2:09 pm

Glad it helped!
Bonnie Jonkman

Envision Energy USA, 2016-
National Renewable Energy Laboratory, 2003-2016


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