# Question about using total energy equation or thermal equation

 User Name Remember Me Password
 Register Blogs Members List Search Today's Posts Mark Forums Read

 LinkBack Thread Tools Display Modes
 May 6, 2013, 13:15 Question about using total energy equation or thermal equation #1 Senior Member     Meimei Wang Join Date: Jul 2012 Posts: 494 Rep Power: 8 HI, The tutorial tell that, for low-speed flow, thermal equation could be used instead of total energy equation to accelerate the computation. But how to know whether my case is 'low-speed' or not? By the way, I'm simulating water. How to know whether the viscous term has to be included or not? __________________ Best regards, Meimei

 May 6, 2013, 14:19 #2 Senior Member     Mr CFD Join Date: Jun 2012 Location: Britain Posts: 312 Rep Power: 7 Only use the total energy equation related to high speed flow if compressibility is important. I think (I invite anyone to correct me here) it's a speed around mach 0.3 and above. If you're using water, and your flow is subsonic you won't have heat generation due to viscous work, so I wouldn't worry about it.

May 6, 2013, 16:40
#3
Senior Member

Meimei Wang
Join Date: Jul 2012
Posts: 494
Rep Power: 8
Quote:
 Originally Posted by RicochetJ Only use the total energy equation related to high speed flow if compressibility is important. I think (I invite anyone to correct me here) it's a speed around mach 0.3 and above. If you're using water, and your flow is subsonic you won't have heat generation due to viscous work, so I wouldn't worry about it.

My flow speed is not that high. Is there is a way (or criteria) to detect whether viscous term need to be included or not?
__________________
Best regards,
Meimei

 May 6, 2013, 18:58 #4 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 12,704 Rep Power: 98 The easiest way is to run a model with and without it and you will then see if it makes a difference.

 Thread Tools Display Modes Linear Mode

 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 OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Mihail CFX 7 September 7, 2014 06:27 saii CFX 2 September 18, 2009 08:07 Harry Dong Main CFD Forum 12 February 4, 2006 01:55 Martin FLUENT 1 January 25, 2001 18:11 Arnold Free Main CFD Forum 0 August 10, 1999 10:18

All times are GMT -4. The time now is 11:42.

 Contact Us - CFD Online - Top