Turb. Kin. Energy - Interpretation ?

Daniel · June 19, 2009, 04:22

Greetings,

I want to present some results of my simulation for my Master thesis. At the moment i am looking for some physical Term to describe the Turbulence of my Flow (not reynolds Number). So is the Turb. Kin. Energy a good Value for this or are there any other usefull physical Terms (Eddy Freq. etc. ) ?

ghorrocks · June 19, 2009, 07:07

Hi,

Sounds like you need a good turbulence modelling textbook. I cna recommend "Turbulence Modelling for CFD" by Wilcox.

In short - turbulence is usually characterised by two variables. The first is usually the intensity expressed as turbulence kinetic energy, and the second can be any of turbulence dissipation, turbulence frequency or turbulent length scales (there are also more obscure second variables but these are the most widely used ones). Of the second variables, all the different types are all linked by correlations after some assumptions are made (eg isotropy) so if you have one you can derive any of the others.

Glenn Horrocks

Daniel · June 20, 2009, 04:06

thanks glenn,

do you mean with the term "turbulence dissipation" the conversion of the kin turb. energy to heat energy ? or how can i understand it.

i am sorry, i have no more time for any deep literture, and i present the results also to people which know basics of fluid mechanics, but they are not specialiced in it. i just need a term or terms for describing how intense my turbulence is at a certain location. so i think, as a first guess to show the tubrulence kin. energy should be the right choice.

ghorrocks · June 20, 2009, 07:04

Hi,

"Deep literature"? I have told you exactly what book to look at! Just go to the library and pick it up. I am not going to write an explanation of turbulence modelling on the forum, that's why they write textbooks on it. I think your last comment is right - if you don't understand the term then don't use it.

Glenn Horrocks

June 19, 2009, 04:22	Turb. Kin. Energy - Interpretation ?	#1
Daniel New Member Join Date: Jun 2009 Posts: 5 Rep Power: 16	Greetings, I want to present some results of my simulation for my Master thesis. At the moment i am looking for some physical Term to describe the Turbulence of my Flow (not reynolds Number). So is the Turb. Kin. Energy a good Value for this or are there any other usefull physical Terms (Eddy Freq. etc. ) ?

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June 19, 2009, 07:07		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	Hi, Sounds like you need a good turbulence modelling textbook. I cna recommend "Turbulence Modelling for CFD" by Wilcox. In short - turbulence is usually characterised by two variables. The first is usually the intensity expressed as turbulence kinetic energy, and the second can be any of turbulence dissipation, turbulence frequency or turbulent length scales (there are also more obscure second variables but these are the most widely used ones). Of the second variables, all the different types are all linked by correlations after some assumptions are made (eg isotropy) so if you have one you can derive any of the others. Glenn Horrocks

June 20, 2009, 04:06		#3
Daniel New Member Join Date: Jun 2009 Posts: 5 Rep Power: 16	thanks glenn, do you mean with the term "turbulence dissipation" the conversion of the kin turb. energy to heat energy ? or how can i understand it. i am sorry, i have no more time for any deep literture, and i present the results also to people which know basics of fluid mechanics, but they are not specialiced in it. i just need a term or terms for describing how intense my turbulence is at a certain location. so i think, as a first guess to show the tubrulence kin. energy should be the right choice.

June 20, 2009, 07:04		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	Hi, "Deep literature"? I have told you exactly what book to look at! Just go to the library and pick it up. I am not going to write an explanation of turbulence modelling on the forum, that's why they write textbooks on it. I think your last comment is right - if you don't understand the term then don't use it. Glenn Horrocks