very low Re number flow

mahzad · June 15, 2012, 07:26

Hi every one
I'm searching for a book or paper in which the physics and characteristics of very low Re flows, I mean Re< 20000 (when the flow is fully laminar), for both steady and unsteady flow have been explaind in a lucid way. does anyone know any good references? would you please introduce some books or papers in case you know any! I want to know more about the effect of viscosity, the behavior of boundary layer and other important factors in these kind of flows!

Thanks for any words in advance!

Mentor Sproxie · June 15, 2012, 09:09

Hi,
I posted a thread provocatively titled: 'one from the vault' - no laminar/turbulent transition - on June 1 2012. Although discussions started out a bit heated, it soon all settled down. The controversial thinking of one past medical researcher, who was sort of 'backed into a corner' over the whole Re number thing and simply forced, due to certain implications Reynolds' work had, as to the validity of his own work (it was said), to then investigate the whole issue independently. There is a strong concurrence with the narrower implications, at least, of this (now deceased medical researcher's findings) on the part of a team at the University of Pennsylvania (the relevant paper was published in 2004). There are claims, also, of there being wider implications, and of that researcher having made certain breakthroughs, pertinent to blood flow physiology and beyond (for fluid dynamics in general)! The links to the websites relating to those somewhat concurring perspectives are to be found in my June 1 thread.
Thanks, M.S.

morteza08 · June 15, 2012, 09:51

Quote:

Originally Posted by mahzad

Hi every one
I'm searching for a book or paper in which the physics and characteristics of very low Re flows, I mean Re< 20000 (when the flow is fully laminar), for both steady and unsteady flow have been explaind in a lucid way. does anyone know any good references? would you please introduce some books or papers in case you know any! I want to know more about the effect of viscosity, the behavior of boundary layer and other important factors in these kind of flows!

Thanks for any words in advance!

hi
These may help you

"Low Reynolds Number Aerodynamics and Transition" ed. by Mustafa Serdar Genç

This book reports the latest development and trends in the low Re number aerodynamics, transition from laminar to turbulence, unsteady low Reynolds flows, experimental studies, numerical transition modelling, control of low Re number flows, and MAV wing aerodynamics.
================================
Wei Shyy, Yongsheng Lian, Jian Tang, Dragos Viieru, Hao Liu, "Aerodynamics of Low Reynolds Number Flyers (Cambridge Aerospace Series)"
=========================
a pdf for creeping flow(re<<1) is attached

FMDenaro · June 15, 2012, 10:32

I am not sure to understand the goal of this topic ... low Re is typical of creep flow (low density), as well as of some flow in micro-device (Re of few hundred).
Transition to turbulence can happen also for low Re number...
What are you thinking about?

mahzad · June 15, 2012, 10:43

I just want to know about the flows at which there is no transition.I mean fully laminar flow I've modeled flow over naca0012 airfoil at re number ranges(re=500, Re=2000, Re=10000) in this range the flow is fully laminar , I want to know about the physics of flow, the effect of viscous force, etc.

FMDenaro · June 15, 2012, 11:09

transition to turbulence is not generalizable, you can have transition in pipe at Re = O(10^3) but not on airfoil (or flat plate) at this Reynolds number. Transition due to geometry is a further case.
You should consider the specific flow problem ...

mahzad · June 15, 2012, 11:38

Quote:

Originally Posted by FMDenaro

transition to turbulence is not generalizable, you can have transition in pipe at Re = O(10^3) but not on airfoil (or flat plate) at this Reynolds number. Transition due to geometry is a further case.
You should consider the specific flow problem ...

Yes, you are completely right, for example I have searched lots of books and paper that parts of which are dedicated to investigation of flow over a circular cylinder, and all of them are in this Re number range, while papers in very low Re flow over airfoil are few. There are some physics of flow which are vague to me. For instance, at this sort of very low Re, total pressure is more than 1 at stagnation point, and it is explained that, it's because of the effect of viscosity. Now I want to know what exactly happens to fluid that ends up with total pressure more than 1 in the stagnation point....!! That's why I'm searching for a book or paper in which explains this kind of phenomena in a lucid way!

Mentor Sproxie · June 15, 2012, 19:28

Hi again, [in 'low Re number' range I mean, of course]
Although my reply (the first here) may have sounded like it didn't relate closely to what you're asking about, it is (at least) about how flow does remain laminar where it has previously/frequently been said not to. The full links to websites which touch on this matter are given in that earlier thread of mine which I mentioned. The domain names which apply are, from memory: 'Laminar-turbulent transition in liquid filled microtubes' (ie. Uni of Pennsylvania 2004)
[OR is effectively about, I must add: the 'lack' of identifiable transition, within a controversial and revealing range, apparently]
And the 'independent' thing IS: www.newdirectionforfluiddynamics.com
There is much contentious discussion to be found, within those sites (including reference to some of those physical properties at play) BUT just ignore this if it's a bit 'off the beam', new as I am to the field. M.S.

June 15, 2012, 07:26	very low Re number flow	#1
mahzad Member mahzad_kh Join Date: Jun 2010 Posts: 38 Rep Power: 15	Hi every one I'm searching for a book or paper in which the physics and characteristics of very low Re flows, I mean Re< 20000 (when the flow is fully laminar), for both steady and unsteady flow have been explaind in a lucid way. does anyone know any good references? would you please introduce some books or papers in case you know any! I want to know more about the effect of viscosity, the behavior of boundary layer and other important factors in these kind of flows! Thanks for any words in advance!

June 15, 2012, 09:09	flow involving anomalously low RE numbers in the microscale	#2
Mentor Sproxie New Member non-anglicised version,originally: Pierre Tourcat Join Date: May 2012 Posts: 6 Rep Power: 13	Hi, I posted a thread provocatively titled: 'one from the vault' - no laminar/turbulent transition - on June 1 2012. Although discussions started out a bit heated, it soon all settled down. The controversial thinking of one past medical researcher, who was sort of 'backed into a corner' over the whole Re number thing and simply forced, due to certain implications Reynolds' work had, as to the validity of his own work (it was said), to then investigate the whole issue independently. There is a strong concurrence with the narrower implications, at least, of this (now deceased medical researcher's findings) on the part of a team at the University of Pennsylvania (the relevant paper was published in 2004). There are claims, also, of there being wider implications, and of that researcher having made certain breakthroughs, pertinent to blood flow physiology and beyond (for fluid dynamics in general)! The links to the websites relating to those somewhat concurring perspectives are to be found in my June 1 thread. Thanks, M.S.

June 15, 2012, 19:28	flow that is both 'low Re' and laminar	#8
Mentor Sproxie New Member non-anglicised version,originally: Pierre Tourcat Join Date: May 2012 Posts: 6 Rep Power: 13	Hi again, [in 'low Re number' range I mean, of course] Although my reply (the first here) may have sounded like it didn't relate closely to what you're asking about, it is (at least) about how flow does remain laminar where it has previously/frequently been said not to. The full links to websites which touch on this matter are given in that earlier thread of mine which I mentioned. The domain names which apply are, from memory: 'Laminar-turbulent transition in liquid filled microtubes' (ie. Uni of Pennsylvania 2004) [OR is effectively about, I must add: the 'lack' of identifiable transition, within a controversial and revealing range, apparently] And the 'independent' thing IS: www.newdirectionforfluiddynamics.com There is much contentious discussion to be found, within those sites (including reference to some of those physical properties at play) BUT just ignore this if it's a bit 'off the beam', new as I am to the field. M.S. Last edited by Mentor Sproxie; June 15, 2012 at 20:06. Reason: minor qualification needed (realised) only a minute after posting

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June 15, 2012, 10:32		#4
FMDenaro Senior Member Filippo Maria Denaro Join Date: Jul 2010 Posts: 6,764 Rep Power: 71	I am not sure to understand the goal of this topic ... low Re is typical of creep flow (low density), as well as of some flow in micro-device (Re of few hundred). Transition to turbulence can happen also for low Re number... What are you thinking about?

June 15, 2012, 10:43		#5
mahzad Member mahzad_kh Join Date: Jun 2010 Posts: 38 Rep Power: 15	I just want to know about the flows at which there is no transition.I mean fully laminar flow I've modeled flow over naca0012 airfoil at re number ranges(re=500, Re=2000, Re=10000) in this range the flow is fully laminar , I want to know about the physics of flow, the effect of viscous force, etc.

June 15, 2012, 11:09		#6
FMDenaro Senior Member Filippo Maria Denaro Join Date: Jul 2010 Posts: 6,764 Rep Power: 71	transition to turbulence is not generalizable, you can have transition in pipe at Re = O(10^3) but not on airfoil (or flat plate) at this Reynolds number. Transition due to geometry is a further case. You should consider the specific flow problem ...