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k-e and TI - Length values

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Old   March 6, 2006, 02:28
Default k-e and TI - Length values
  #1
saravanan
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Hi

I am cfd beginner.I would like to know how the values of kinetic energy,dissipation or Turbulence Intensity and Length is calculated that is given in define boundary condition panel of starcd for inlet.And how kinetic energy and dissipation is connected to Turbulence Intensity and Length.Is there any mathematical relations?Please let me know. Thanks and Regards

saravanan

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Old   March 7, 2006, 02:17
Default Re: k-e and TI - Length values
  #2
sundar
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I ADVISE U TO READ THE METHODOLOGY VOLUMES AND USER GUIDE THAT COMES WITH STAR-CD.YOU'VE SUFFICIENT GUIDELINES IN 'EM.GOOD LUCK!!!
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Old   March 7, 2006, 14:37
Default Re: k-e and TI - Length values
  #3
Hubert Janocha
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Yes, reading the methodology and other literature is one thing.

the problem is not very serious. This data belongs only to the boundaries. A little bit away from the boundary the flow knows it length scala and the other turb. data.

So make a little extrusion of your inlet boundary. When the flow reaches the area of interest in your geometriy, it has got already the right values for the turbulance. If you have to know it more acuratly check the velocity profile turb. kinetic energy and siispation near the geometry wall.

For stability and convergency reasons The outlet boundary should always be a little extruded. Additionally you can give the "zero gradient" setting for turbulance.

To give a good guess of values, carry out some calculations and see in the postprocessing the values of dissipation, length scale and so on, for the main flow area.

Good luck

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