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

Inviscid flow calculator, Entropy rise?!!

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   April 8, 2003, 12:21
Default Inviscid flow calculator, Entropy rise?!!
  #1
MJK
Guest
 
Posts: n/a
Hello there,

I was wondering how is possible that inviscid flow calculators (Euler Solvers) can predict entropy rise correctly?

Noting that viscoity and thermal conductivity are the only means which could produce loss and they are taken to be zero in inviscid flow, then how is it possible to have irreversibilities due to shocks when inviscid model is used?

Thanks

MJK
  Reply With Quote

Old   April 8, 2003, 12:42
Default Re: Inviscid flow calculator, Entropy rise?!!
  #2
Pao
Guest
 
Posts: n/a
you have artificial viscosity in Euler code. Have you noticed total pressure loss at lot at low Mach in Euler code when there is reverse flow?
  Reply With Quote

Old   April 8, 2003, 12:51
Default Re: Inviscid flow calculator, Entropy rise?!!
  #3
MJK
Guest
 
Posts: n/a
Thanks Pao,

Right. For central schemes like Jameson's you set artifitial viscosity to a value giving you right answer.

But smarter scheme like upwind usually need no setting for artifitial diffusion and they still give a correct answer! So how smart should be these schemes with no tuning, they automatically feed in a right amount of artifitial diffusion to predict entropy rise correctly.

Thanks again

MJK
  Reply With Quote

Old   April 9, 2003, 04:36
Default Re: Inviscid flow calculator, Entropy rise?!!
  #4
Kevin
Guest
 
Posts: n/a
The dissipation in the inviscid schemes is needed for stability purpose.

The entropy rise (jump) accros a shock is generated by the discontinuity of the computed value : Euler equations fulfil the Rankine-Hugoniot jump relations and so give an entropy rise.

I don't know if it's right or complete but maybe it will help you.

Regards,

Kevin
  Reply With Quote

Reply


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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Heat transfer Inviscid pipe flow Dave CFX 4 March 6, 2008 11:33
oscillating airfoil in an inviscid fluid flow S.T Main CFD Forum 6 December 10, 2007 09:07
modelling inviscid 2D flow at high angle of attack Ferdinando FLUENT 2 October 30, 2007 18:26
flow simulation across a small fan jane luo Main CFD Forum 15 April 12, 2004 18:49
Inviscid flow Atit Koonsrisuk CFX 12 January 2, 2003 13:40


All times are GMT -4. The time now is 04:43.