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

wrong velocity & temp at initialization

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

Reply
 
LinkBack Thread Tools Display Modes
Old   October 15, 2007, 08:15
Default wrong velocity & temp at initialization
  #1
Leo
Guest
 
Posts: n/a
I've got an Issue concerning total gauge pressure. I know this topic has been discussed numerous times, but so far I have not come across a thread, that would answer my particular question.

I work on simulating a free-flow at M=0.8, p_stat=26436.2426 Pa, and T=223.15K. I calculated the total pressure to be p_tot=40297.8223 Pa and the total temperature to be T_tot=251.7132.

I set the Operating Pressure to "0", input the p_tot for the Pressure Inlet at "Total Gauge Pressure", p_stat at Initial Gauge Pressure and T_tot at Total Temperature. So far so good.

When I want to initialize the calculation and set "compute from" to my Pressure Inlet, Fluent puts out a Gauge Pressure of 26436.18 Pa (not too far off), a velocity of 222.9477 m/s (at T=223.15 and 0.8M it should have been 239.704) and a temperature of 165.1291 (now, where did this come from). Via try and fail I found out that when I input a Total temperature of 323.2376 K and a Total Gauge Pressure of 38293.5 Pa I get the desired Initial Values. These Inputs don't mirror the real conditions though, so I wonder what I could be missing here.

Regards, Leo
  Reply With Quote

Old   October 15, 2007, 10:42
Default Re: wrong velocity & temp at initialization
  #2
Leo
Guest
 
Posts: n/a
By the way - this problem occurs only, when in the material's setup cp is turned to kinetic energy.
  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
Problem with assigned inlet velocity profile as a boundary condition Ozgur_ FLUENT 5 August 25, 2015 04:58
Compare 2D axi-symmetric and 3D. Is OpenFOAM calculate the velocity wrong? RalphS OpenFOAM 6 November 13, 2010 21:51
The velocity of wall boundary condtion Dhb FLUENT 1 January 14, 2010 14:00
Inlet Velocity in CFX aeroman CFX 12 August 6, 2009 18:42
Influece of wall velocity in the main flow marvin CFX 0 March 22, 2008 03:05


All times are GMT -4. The time now is 17:00.