Low Reynolds Number Flow Computation

January 22, 2002, 03:42

Hi,

What are the difficulties in the computation of low Reynolds number viscous flow?

Thank you in advance.

January 22, 2002, 04:13

Low Reynolds number viscous flow - no problem! It's very simple!

January 22, 2002, 04:42

It depends on Mach number. If M is not small (for example > 1) this problem is not "very simple!"

Alexey

January 22, 2002, 06:35

If Mach number too big -> Reynolds number not small!

January 22, 2002, 08:55

If the scale of your simulation is of the order of hundreds of micro meters or less, you might have some problems with boundary conditions. For instance, no slip b.c.'s may not be valid. Especially, this problem arises when Mach number is large.

January 22, 2002, 09:28

Does that not depent on weather the assumption of the fluid being a continuum holds ? ie. if we have a thin low pressure gas and small dimensions, then the eq. we normally use are not valid.

Christian

January 22, 2002, 11:16

plz send me books on this topic and on cfd thanks

mukkarum

new one in cfd

January 22, 2002, 12:01

Situation when Re is small and M is big may take place when gas is strongly rarefied. In this case either Navier-Stokes or Boltzmann equations are used depending on Knudsen number.

=Alexey

January 22, 2002, 03:42	Low Reynolds Number Flow Computation	#1
A.M.Yang Guest Posts: n/a	Hi, What are the difficulties in the computation of low Reynolds number viscous flow? Thank you in advance.

January 22, 2002, 04:13	Re: Low Reynolds Number Flow Computation	#2
Andrey Guest Posts: n/a	Low Reynolds number viscous flow - no problem! It's very simple!

January 22, 2002, 04:42	Re: Low Reynolds Number Flow Computation	#3
Alexey Guest Posts: n/a	It depends on Mach number. If M is not small (for example > 1) this problem is not "very simple!" Alexey

January 22, 2002, 06:35	Re: Low Reynolds Number Flow Computation	#4
Andrey Guest Posts: n/a	If Mach number too big -> Reynolds number not small!

January 22, 2002, 08:55	Re: Low Reynolds Number Flow Computation	#5
Farshid Guest Posts: n/a	If the scale of your simulation is of the order of hundreds of micro meters or less, you might have some problems with boundary conditions. For instance, no slip b.c.'s may not be valid. Especially, this problem arises when Mach number is large.

January 22, 2002, 09:28	Re: Low Reynolds Number Flow Computation	#6
Christian Holm Guest Posts: n/a	Does that not depent on weather the assumption of the fluid being a continuum holds ? ie. if we have a thin low pressure gas and small dimensions, then the eq. we normally use are not valid. Christian

January 22, 2002, 11:16	Re: Low Reynolds Number Flow Computation	#7
mukkarum hussain Guest Posts: n/a	plz send me books on this topic and on cfd thanks mukkarum new one in cfd

January 22, 2002, 12:01	Re: Low Reynolds Number Flow Computation	#8
Alexey Guest Posts: n/a	Situation when Re is small and M is big may take place when gas is strongly rarefied. In this case either Navier-Stokes or Boltzmann equations are used depending on Knudsen number. =Alexey

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