Memory Requirements for full-field wind arrays

Wind & Water Computer-Aided Engineering Software Tools
1

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

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

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

FFArrayElements = 3*NZGrids*NYGrids*NumTimeSteps

The formula for bytes and GBs is left as an exercise for the student. :stuck_out_tongue:

2

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: wind.nrel.gov/public/bjonkman/De … Sizes.xlsx

3

Bonnie, that is a life saving spreadsheet you shared there. I was not looking forward to calculating the file sizes at all. Many thanks!

4

Glad it helped!

5

You can now find the lost Excel file from the link above on GitHub: TurbSim/TurbSim_v150_GridSizes.xlsx at master · old-NWTC/TurbSim · GitHub