Flow past a sphere

Muhammed_iraq · December 17, 2009, 17:10

Quote:

Originally Posted by thecfduser

Hi
For the realtion between Re and Nu, i dont know it, but it is sure that u can find a lot of correlations in bibilography...
For the Strouhal number, it is not easy... U must monitor data in a point that is behind ure sphere, then give this data to Matlab and do a fast fourrier transform to get the frequency of ure eddies....Once u have this frequency, u can calculate the Stouhal number...I dont know if this number is affected by temperature in ure case...
Regards

dear Karine
please give me the options of fluent to reach strouhal number field
i am waiting your reply
regards

thecfduser · December 17, 2009, 18:47

Hi Muhammed
I dont know how to do it in Fluent
I do it on Matlab
In fluent, put a point behind ure sphere and monitor velocity in it. The data that u will get, u must treat it on Matlab with a fast fourrier transform to get the frequency of ure coherent structures. If ure Re is <120 (i think) u will not get any vortex schedding: u will get a toroidal vortex....

(there is no strouhal number field: there is ONE Strouhal number in ure flow)

Hope that i was clear

Muhammed_iraq · December 18, 2009, 04:00

Quote:

Originally Posted by thecfduser

Hi Muhammed
I dont know how to do it in Fluent
I do it on Matlab
In fluent, put a point behind ure sphere and monitor velocity in it. The data that u will get, u must treat it on Matlab with a fast fourrier transform to get the frequency of ure coherent structures. If ure Re is <120 (i think) u will not get any vortex schedding: u will get a toroidal vortex....

(there is no strouhal number field: there is ONE Strouhal number in ure flow)

Hope that i was clear

Dear Karine
in the past and by chance and from options of fluent , i found the box contain Strouhal Number but i forget the option and help of my fluent not found in my computer,please can you find this option from your help of your fluent ,can you send example in the matlab in order to strouhal Number to my e-mail(muham76@yahoo.com)
i am waiting your reply
many thanks

thecfduser · December 18, 2009, 16:32

Hi
In fact, Fluent is able to do a FFT but i had ever tried it....it is bette anyway to do it on matlab ot mathematica...
for matlab i dont have it for instance to help u ...sorry...but if i rememeber good, the function name is FFT
hope that somebody can help u more

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December 17, 2009, 18:47		#22
thecfduser Senior Member karine Join Date: Nov 2009 Posts: 158 Rep Power: 16	Hi Muhammed I dont know how to do it in Fluent I do it on Matlab In fluent, put a point behind ure sphere and monitor velocity in it. The data that u will get, u must treat it on Matlab with a fast fourrier transform to get the frequency of ure coherent structures. If ure Re is <120 (i think) u will not get any vortex schedding: u will get a toroidal vortex.... (there is no strouhal number field: there is ONE Strouhal number in ure flow) Hope that i was clear

December 18, 2009, 16:32		#24
thecfduser Senior Member karine Join Date: Nov 2009 Posts: 158 Rep Power: 16	Hi In fact, Fluent is able to do a FFT but i had ever tried it....it is bette anyway to do it on matlab ot mathematica... for matlab i dont have it for instance to help u ...sorry...but if i rememeber good, the function name is FFT hope that somebody can help u more