CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM Running, Solving & CFD

Resistance boundary conditions

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

Reply
 
LinkBack Thread Tools Display Modes
Old   September 13, 2007, 21:57
Default Hey Guys: Has anybody here
  #1
Member
 
Ning Yang
Join Date: Mar 2009
Location: University Park, PA, USA
Posts: 85
Rep Power: 7
nzy102 is on a distinguished road
Hey Guys:

Has anybody here used resistance outflow boundary condition in openfoam? Basically what it does is to keep the ratio (resistance R) bewteen pressure P and flow rate Q constant at the outlet, instead of using constant pressure or other outlet boundary conditions? Assume that the pressure on the outlet cross section is constant.

Thank you.

Ning
nzy102 is offline   Reply With Quote

Old   September 14, 2007, 05:03
Default Hi Ning, If I'm not getting w
  #2
Super Moderator
 
Takuya OSHIMA
Join Date: Mar 2009
Location: Niigata City, Japan
Posts: 516
Blog Entries: 1
Rep Power: 10
7islands is on a distinguished road
Hi Ning,
If I'm not getting wrong might this thread be of any help to you? ...or not?

Takuya
7islands is offline   Reply With Quote

Old   September 15, 2007, 12:09
Default Hi Takuya: Thank you for sh
  #3
Member
 
Ning Yang
Join Date: Mar 2009
Location: University Park, PA, USA
Posts: 85
Rep Power: 7
nzy102 is on a distinguished road
Hi Takuya:

Thank you for sharing your code. It is pretty close. The only difference is that I need to replace normal velocity by integral surface flow rate. The problem is when I tried to compile your code, I got some error like:

make: *** No rule to make target `/derived/normalIncidenceAcousticImpedance/normalIncidenceAcousticImpedanceFvPat chScalarField.dep', needed by `Make/linux64GccDPOpt/dependencies'. Stop.

Can you let me know why this happened? Thank you.

Ning
nzy102 is offline   Reply With Quote

Old   September 17, 2007, 21:22
Default Hi Ning, Well, there are vari
  #4
Super Moderator
 
Takuya OSHIMA
Join Date: Mar 2009
Location: Niigata City, Japan
Posts: 516
Blog Entries: 1
Rep Power: 10
7islands is on a distinguished road
Hi Ning,
Well, there are various things you have to be careful about the code, at least:
  • as the posted date of the code obviously indicates, the code is to be used with OF 1.3. For newer OF versions you need to make modifications accordingly.
  • as the code was meant to be just an proof-of-cocept, it just calculates boundary p or U based on patch-internal cell-center value of the opposite variable (with the b. c. type set to zeroGradient). If you intend to make serious use of the code numerical discretization schemes must be carefully cosidered besides modification from flow velocity to flow rate.
Actually I myself no longer use nor maintain the code so you have to do above by yourself. Still, it should serve as a much better starting point compared to writing it from scratch all by yourself.

Good luck,
Takuya
7islands is offline   Reply With Quote

Old   September 17, 2007, 22:23
Default Thank you for your reply. I fi
  #5
Member
 
Ning Yang
Join Date: Mar 2009
Location: University Park, PA, USA
Posts: 85
Rep Power: 7
nzy102 is on a distinguished road
Thank you for your reply. I figured the problem out and now I don't have any compilation errors. I have one more question though: can you explain the following line in your code?

operator==(2.0 * z_ * (n & Up) - *this);

It doesn't ring a bell for me. Thank you.

Ning
nzy102 is offline   Reply With Quote

Old   September 19, 2007, 20:14
Default Hi Ning, It's an #if 0'ed l
  #6
Super Moderator
 
Takuya OSHIMA
Join Date: Mar 2009
Location: Niigata City, Japan
Posts: 516
Blog Entries: 1
Rep Power: 10
7islands is on a distinguished road
Hi Ning,

It's an #if 0'ed line anyway so please don't care. It's an updating equation if velocity and pressure are teken staggered in time ((*this<sub>new</sub> + *this<sub>old</sub>) / 2 = z_ * (n & Up)).

Takuya
7islands is offline   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
Burgerbs equation non constant Boundary Conditions Initial Conditions arkangel OpenFOAM Running, Solving & CFD 1 October 2, 2008 14:48
Boundary conditions for turbulent boundary layer Thomas FLUENT 1 June 17, 2008 05:14
boundary conditions for boundary layer flow A. Al-zoubi CFX 0 November 3, 2007 08:11
boundary conditions for compute resistance of ship Bruce CFX 1 April 18, 2007 11:30
Integral boundary conditions turbulent intensitylength boundary conditions olesen OpenFOAM Running, Solving & CFD 0 July 27, 2006 07:18


All times are GMT -4. The time now is 19:35.