# k and epsilon

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 June 26, 2010, 04:36 k and epsilon #1 Member   Hamed Join Date: Oct 2009 Posts: 64 Rep Power: 9 Sponsored Links Dear all, I want to model a centrifugal pump in NUMECA using k-eps turbulence model, how ever I just have intensity and length scale at inlet, how can I convert intensity and length scale to k and epsilon at inlet ? sincerely

 June 30, 2010, 07:06 #2 Senior Member   Hamid Zoka Join Date: Nov 2009 Posts: 210 Rep Power: 11 Dear Hamed; if pump inlet velocity is known, ( inlet velocity may be calculated by knowing pump flow rate and pump suction side diameter) you can find k from turbulence intensity relation. calculated k can be applied to length scale relation to find epsilon. does it help?

 January 24, 2011, 09:44 #3 New Member   sanboju Join Date: Jan 2011 Posts: 14 Rep Power: 8 Hi Amed, Sorry because the late answer. As you know, k is the kinetic energy and epsilon is the disipation of turbulence. We could consider epsilon as 0.1*k. The kinetic energy k, can be calculated as: k=3/2 (T*U)^2, where T is the Temperature of the problem, and U is the inlet velocity. I hope I'll be helpful. Cheers

 January 26, 2011, 12:10 Tu #4 New Member   sanboju Join Date: Jan 2011 Posts: 14 Rep Power: 8 Hi, Sorry because of the definition of the other day. As you know in a turbulence model, the units for k are [m^2/s^2]. I was wrong saying T was the temperature of the model, T is is a percentatge that represents the turbulence intensity factor as I've seen on biography. I realise because of my job results, intensity of the turbulence and the poor disipation. T = 0.05-0.10 (biography, fluctuations respecte wind velocity) U= inlet velocity Sorry if someone have run their jobs after my definition of k but I wouldn't get results yet. k= 3/2(T*U)^2 epsilon = 0.1*k Greatings, sanboju

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