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integral length scale and cross-correlation (with openfoam data, LES pipe flow)Hi,
i want to calculate the integral length scale of a pipe flow in matlab. the pipe flow (LES) is calculated with openfoam-1.6 . I have read out the velocity components (cell center) of 1000 cells in a preview-folder at a one definite time-step. Now I have to calculate the cross-correlation function (in x-direction): 1. step: i subtract the mean velocity from the axial-velocity-component in order to obtain the fluctuating velocity u' 2. step: i calculate the cross-correlation as: for i=1:1:1000; ufluct(i)=uflukt(1)*uflukt(i) end ucross=ufluct./ufluct(1); ufluct is the same as u' and ucross should be my cross-correlation coefficient?! but my problem is, my code does not calculate the time-averaged cross-correlation-coefficient because i don't know wich kind of data i have to time-averaged.:confused: i have read some books about it (Pope, Wilcox, Hinze and Lumley ...) but i can't implement their ideas in matlab.:mad: it would be great if somebody has an idea or could explain me how to calculate the integral length scale correctly! best regards, jet |

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