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vijesh joshi May 5, 2006 23:59

turbulence concept!!!
 
Hello friends. I saw turbulence 1%, 5%, 10% & above in CFX. But what is the concept behind these words? What actually happens in the solver when we choose the desired turbulence model? These two are my questions. Thank you.

dh May 6, 2006 07:16

Re: turbulence concept!!!
 
The percentages refer to turbulence intensity. The documentation in "Turbulence and Near Wall Theory" explains the modelling concepts of all turbulence models in CFX.

Ben Akih May 7, 2006 20:18

Re: turbulence concept!!!
 
hi vijesh! as already mentioned by dh, those percentages refer to the turbulence intensity in the flow. it is the percental ration of the rms of the fluctuating part of the velocity to the mean steady velocity. that 1% would mean that the rms of fluctuation is 0.01 times the average velocity of the flow. most turbulence model require the specification of this intensity and a length scale or time scale. from these two parameters, the dissipation is computed and the local eddy viscosity is determined. the effective viscosity is then used in the Reynolds-averaged navier stokes. best thing is always to look up what the different parameters mean in the cfx help manual.



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