Flow regime identification

dvolkind · April 10, 2011, 15:28

Greetings to everyone!

Can anyone please explain me how to identify the flow regime?
For example, if I have the flow properly resolved (or precise experimental data is available), so that all characteristics of the flow are known everywhere at every timestep, how do I determine whether the flow is laminar, turbulent or transitional?

Thanks in advance,
Dmitry

ghorrocks · April 10, 2011, 23:23

If turbulent it will have a turbulence spectrum covering a wide range of time and spacial scales. A laminar flow will have only a limited range of time and space scales.

dvolkind · April 11, 2011, 10:06

Thank You, Glenn! Could you please explain what is considered wide or limited range?

ghorrocks · April 11, 2011, 19:35

Go to your library and look at any textbook on turbulence modelling or turbulence theory. This is all basic turbulence modelling theory and should be explained in detail by any decent textbook. The text I use is "Turbulence modelling for CFD" by Wilcox, but there are many others.

dvolkind · April 12, 2011, 04:09

Thanks again! I'll try to find some books. It has become really difficult, because foreign technical books are no longer published since USSR(

ghorrocks · April 12, 2011, 08:32

Then you should be able to find a USSR turbulence textbook. There are lots of textbooks on the topic so I bet you can find a Russian one.

April 10, 2011, 15:28	Flow regime identification	#1
dvolkind Member Dmitry Volkind Join Date: Jan 2010 Location: Ekaterinburg, Russia Posts: 64 Rep Power: 16	Greetings to everyone! Can anyone please explain me how to identify the flow regime? For example, if I have the flow properly resolved (or precise experimental data is available), so that all characteristics of the flow are known everywhere at every timestep, how do I determine whether the flow is laminar, turbulent or transitional? Thanks in advance, Dmitry

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April 10, 2011, 23:23		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	If turbulent it will have a turbulence spectrum covering a wide range of time and spacial scales. A laminar flow will have only a limited range of time and space scales.

April 11, 2011, 10:06		#3
dvolkind Member Dmitry Volkind Join Date: Jan 2010 Location: Ekaterinburg, Russia Posts: 64 Rep Power: 16	Thank You, Glenn! Could you please explain what is considered wide or limited range?

April 11, 2011, 19:35		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	Go to your library and look at any textbook on turbulence modelling or turbulence theory. This is all basic turbulence modelling theory and should be explained in detail by any decent textbook. The text I use is "Turbulence modelling for CFD" by Wilcox, but there are many others.

April 12, 2011, 04:09		#5
dvolkind Member Dmitry Volkind Join Date: Jan 2010 Location: Ekaterinburg, Russia Posts: 64 Rep Power: 16	Thanks again! I'll try to find some books. It has become really difficult, because foreign technical books are no longer published since USSR(

April 12, 2011, 08:32		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	Then you should be able to find a USSR turbulence textbook. There are lots of textbooks on the topic so I bet you can find a Russian one.