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

How to calculate Entropy in CFD as a state variabl

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

Reply
 
LinkBack Thread Tools Display Modes
Old   July 7, 2008, 11:01
Default How to calculate Entropy in CFD as a state variabl
  #1
Vinayender
Guest
 
Posts: n/a
Hi all,

Can any one help me how to calculate Entropy in CFD as a state variable instead of calculating change in entropy between two states.

Thanks, Vinayender.
  Reply With Quote

Old   July 7, 2008, 15:22
Default Re: How to calculate Entropy in CFD as a state var
  #2
Ananda Himansu
Guest
 
Posts: n/a
In classical thermodynamics, absolute entropy enters only in a very restricted way via the Nernst postulate of the pure crystalline state of some substances. I would not play around with this. Otherwise, in classical thermodynamics, entropy is indeed a state variable, but it is defined only to within an arbitrary constant (ignoring the Nernst postulate / third law). Hence, you can only know entropy relative to an arbitrary reference state, which is equivalent to calculating the change in entropy between two states. Just define the entropy of the pure substance you are considering to be zero in some reference state. After that, its value in any other state is well defined by any valid reversible process that will take the substance from the reference state to the final state. You have consistently take into account changes in entropy during phase changes and changes in chemical composition, etc.

  Reply With Quote

Old   July 8, 2008, 06:42
Default Re: How to calculate Entropy in CFD as a state var
  #3
Vinayender
Guest
 
Posts: n/a
Hi Ananda,

Thank you very much for your comment.

Thanks, Vinayender.
  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
calculate the state in drainage piping. ota Phoenics 0 October 14, 2007 01:35
How to calculate without CFD program KP Main CFD Forum 2 April 23, 2001 04:58
CFD Symposium (Call for Papers) Chris R. Kleijn Main CFD Forum 0 October 5, 1998 10:25
ASME CFD Symposium - Call for Papers Chris R. Kleijn Main CFD Forum 0 September 8, 1998 08:19
ASME CFD Symposium - Call for Papers Chris R. Kleijn Main CFD Forum 0 September 3, 1998 08:45


All times are GMT -4. The time now is 11:27.