RANLUX pseudorandom numbers

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Timo.Strotbaum
Posts: 4
Joined: Mon Jun 04, 2018 10:18 am
Organization: RWTH Aachen
Location: Germany

RANLUX pseudorandom numbers

Postby Timo.Strotbaum » Mon Jul 23, 2018 11:39 am

Hello,

I´m currently generating several turbulent wind files with the same Input file. The First Random Seed is a number, the second is set to RANLUX.
Therefore i was expexting to get different wind files, but the summary file of all my turbsim files says exactly the same:

Code: Select all

Harvested Random Seeds after Generation of the Random Numbers:

    889678805 K1
            0 K2

and thus the wind files are all the same.
Can Anyone Help?

Thanks in advance,

Timo

Jason.Jonkman
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Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
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Re: RANLUX pseudorandom numbers

Postby Jason.Jonkman » Mon Jul 23, 2018 1:01 pm

Dear Timo,

I'm not sure I understand your question. You say you are generating several turbulent wind files with the same TurbSim input file. Are you changing the random seed between each input file, but get the same harvested seed in the summary file regardless?

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov

Timo.Strotbaum
Posts: 4
Joined: Mon Jun 04, 2018 10:18 am
Organization: RWTH Aachen
Location: Germany

Re: RANLUX pseudorandom numbers

Postby Timo.Strotbaum » Mon Jul 23, 2018 2:42 pm

Dear Mr. Jonkman,

thank you for your quick reply. Yes, I thought by selecting RANLUX for the second seed, i thought i´d get different results. I guess that assumption was wrong? Then i don´t get what the difference between selecting 2 random numbers by myself and one random number with the second Seed RANLUX is?

Best regards,

Jason.Jonkman
Posts: 3753
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: RANLUX pseudorandom numbers

Postby Jason.Jonkman » Mon Jul 23, 2018 3:04 pm

Dear Timo,

When RandSeed1 and RandSeed2 in TurbSim are both set to numerical values, TurbSim will use an intrinsic (compiler-specific) pseudo-random-number generator (pRNG). When RandSeed2 is set to "RanLux", TurbSim will use a different pseudo-random-number generator that only requires one seed. See the TurbSim User's Guide for more information.

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov


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