# autocorrelation in Matlab

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 August 11, 2016, 02:53 autocorrelation in Matlab #1 New Member   Alessandro Join Date: Jul 2016 Posts: 10 Rep Power: 5 Dear all, I am trying to plot the energy spectrum from the autocorrelation function. For this aim I am using the velocity fluctuation of a point of the domain varying through the time. the expression of the autocorrelation from Pope is: /^2, so in case s=0 the autocorrelation is 1. The code that I have written in Matlab is: u_primequad=zeros(n,1); %autocorr=0; for i=1:n-1 u_primequad(i,1)=((u_prime(i)*u_prime(i))); end u_primequad=mean(u_primequad); f=zeros(n,1); autocorr=zeros(n,1); for j=0:n-1 for i=1:n-j autocorr(i,1)=(u_prime(i)*u_prime(i+j)); end autocorr1=mean(autocorr); f(j+1,1)=autocorr1/u_primequad; end Someone can say me if are there some errors? Thank you in advance

 August 12, 2016, 10:12 #2 Super Moderator     Tobias Holzmann Join Date: Oct 2010 Location: Augsburg Posts: 2,343 Blog Entries: 6 Rep Power: 40 Hi, I think you missed the correct forum. This forum is about OpenFOAM and not Matlab (: __________________ Keep foaming, Tobias Holzmann

 July 13, 2019, 03:06 #3 Senior Member   Jianrui Zeng Join Date: May 2018 Location: China Posts: 157 Rep Power: 3 I am doing DNS of pipe flow, and I am wondering how to do autocorrelation using Matlab? Thank you.

August 20, 2019, 07:03
#4
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Arijit Saha
Join Date: Feb 2019
Location: Singapore
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Quote:
 Originally Posted by calf.Z I am doing DNS of pipe flow, and I am wondering how to do autocorrelation using Matlab? Thank you.
Did you get how to do it?
I m in a great need.
Will be very helpful if you share.

September 4, 2019, 03:47
#5
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Jianrui Zeng
Join Date: May 2018
Location: China
Posts: 157
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Quote:
 Originally Posted by ari003 Did you get how to do it? I m in a great need. Will be very helpful if you share.
I am still researching it, we can keep contact if we make any progress.

March 24, 2020, 07:22
#6
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Chia-Chun Chu
Join Date: Mar 2020
Location: Taiwan
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Quote:
 Originally Posted by calf.Z I am still researching it, we can keep contact if we make any progress.
Excuse me. Did you get the correct answer? I also encountered the same problem. May you share the solution to this problem for me?