CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > FLUENT

Nondimensionalization in FIDAP

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   June 23, 2002, 19:38
Default Nondimensionalization in FIDAP
  #1
Andrew Ward
Guest
 
Posts: n/a
Hello Fluent users,

I have a simulation involving turbulence, compressibility, and multiple species, the equations for which I'm trying to make dimensionless. The Reynold's number for the flow is about 6E5.

I'm interested in what happens to material properties such as specific heat when multiple species are involved in the flow. For flows not involving species, the dimensionless specific heat is typically set equal to unity. If there are multiple species, however, I'm wondering if the dimensionless specific heat for each species is 1) set to unity, or 2) divided by the same reference value (the carrier fluid, for instance).

For instance, if the carrier fluid is air for which Cp is about 1006 J/kgK, and other species are CO (1041) and HCl (800), the normalised values may all be 1, or they may be 1, 1.03 and 0.768 respectively).

I would greatly value some advice on which is the correct way to normalise this and other material properties. Thank you very much for your help.

Regards,

Andrew C. Ward

Department of Chemical Engineering The University of Queensland

  Reply With Quote

Old   June 23, 2002, 20:14
Default Re: Nondimensionalization in FIDAP
  #2
Jin-Wook LEE
Guest
 
Posts: n/a
Of course, the specific heat for each species is divided by the same reference value.

Sincerely, Jinwook

  Reply With Quote

Old   June 23, 2002, 23:37
Default Re: Nondimensionalization in FIDAP
  #3
Andrew Ward
Guest
 
Posts: n/a
Thank you, Jinwook. This is very helpful.

I've since been looking again at the FIDAP Tutorial Manual. To normalise diffusivity when there are multiple species, it suggests setting the diffusivity for species n to 1/Pe_n, where Pe_n is the mass transport Peclet number.

In light of Jinwook's response about specific heat (normalise each species by the same thing), I wonder if what the manual says makes sense.

Any further comments would be more than welcome.

Regards,

Andrew C. Ward
  Reply With Quote

Old   June 24, 2002, 04:23
Default Re: Nondimensionalization in FIDAP
  #4
Greg Perkins
Guest
 
Posts: n/a
Is it necessary to make the equations non-dimensional??

Its possible to simulate problems for various values of non-dimensional groups, by setting the appropriate values of the physical properties and ensuring they form the non-dimensional values you need.

It may also be that the code adds additional scaling to the equations before solving them anyway. For example in the old Fluent, densities were scaled by a reference density in some model.

You may need to be very careful of your scaling in order to get everything right. Perhaps its easier to check that different combinations of individual physical values which give the same non-dimensional groupings yield the same solution. And then just use one such set of values....

Greg
  Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Fidap to Fluent Ravi FLUENT 3 July 10, 2008 13:31
user_sub FIDAP doesnt work semetay FLUENT 3 July 22, 2006 19:51
how to apply mixed BC by using Fidap subroutine? Ning Yang FLUENT 0 November 23, 2004 20:50
run fidap ? christophe moutet FLUENT 0 July 25, 2002 15:14
Variable Density - Free Surface with FIDAP Vitaliy Pavlyk FLUENT 7 May 2, 2000 15:56


All times are GMT -4. The time now is 16:06.