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

Why is rhoPimpleFoam not fully compressible?

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

Like Tree2Likes
  • 2 Post By sharonyue

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   February 17, 2024, 16:03
Question Why is rhoPimpleFoam not fully compressible?
  #1
New Member
 
Join Date: May 2019
Posts: 10
Rep Power: 7
Pablok is on a distinguished road
Dear CFD Online community,

I'm a PhD student actually dealing with the reactingFoam solver, which I use for combustion simulation. I intend to modify it and add some functionalities (differential diffusion model, conjugate heat transfer, acoustic boundaries conditions ...).

First I'm trying to fully understand the reactingFoam solver and its implementation. It uses the rhoPimpleFoam solver, which is a pressure based solver for compressible flow.

I recently saw this video https://www.youtube.com/watch?v=HZwvtLgxJy4&t=5269s, which is a webinar of Prof. Hrvoje Jasak talking about reacting flow in OpenFoam.
At about 1:28:40 of the video someone says that: "rhoPimpleFoam isn't really compressible".
Prof. Hrvoje Jasak then gave an explanation that I didn't fully understand, isn't a solver considered compressible when it takes into account the density variations? Or this definition is incomplete?

Thanks for your help!

Pablo

Last edited by Pablok; February 20, 2024 at 09:01. Reason: typo
Pablok is offline   Reply With Quote

Old   February 20, 2024, 08:44
Default
  #2
Senior Member
 
Dongyue Li
Join Date: Jun 2012
Location: Beijing, China
Posts: 849
Rep Power: 18
sharonyue is on a distinguished road
For compressible flows, some are doing calculations with really high Mach number, some are doing heat transfer with weak compressibility. The student said "rhoPimpleFoam is not a really compressble solver" by admiting that "only density-based solver is a real compressible solver", like that Roe method or HLL method, and any other kind of approximate Riemann solver. In this case, rhoCentralFoam is a real compressible solver which employs central scheme and Roe/HLL scheme can be implemented similarly.

As Hrv said, rhoPimpleFoam is also a highly validated solver but its pressure-based solver instead of a density based solver. It does not have the entropy fix so for those who do reseach mainly on hyperbolic equations, rhoPimpleFoam is not perfect. Oh the otherhand, rhoPimpleFoam is good enough to capture good shock resolution and other numerical aspects, maybe not high enough resolution though.
hogsonik and Pablok like this.
__________________
My OpenFOAM algorithm website: http://dyfluid.com
By far the largest Chinese CFD-based forum: http://www.cfd-china.com/category/6/openfoam
We provide lots of clusters to Chinese customers, and we are considering to do business overseas: http://dyfluid.com/DMCmodel.html
sharonyue is offline   Reply With Quote

Old   February 25, 2024, 14:24
Default
  #3
New Member
 
Join Date: May 2019
Posts: 10
Rep Power: 7
Pablok is on a distinguished road
Hi Sharonyue,
Thank you very much for your quick answer. It is more clear now.

I compared "rhoCentralFoam" with "sonicFoam" which is the implicit pressure-based solver on the "forwardStep" case. For sonicFoam, the shock waves pattern after some time is smeared and does not have high resolution (see attachment to illustrate: rhoCentralFoam left vs sonicFoam right). I guess that in this case a density based solver is more suited.

For my case, at the moment I mostly do combustion simulation but at low Mach numbers in openfoam (using "reactingFoam"). So implicit pressure-based solver should be fine for now.

Pablo
Attached Images
File Type: jpg rhoCentralFoam_sonicFoam.jpg (26.6 KB, 26 views)
Pablok is offline   Reply With Quote

Reply

Tags
compressible, density based solver, reactingfoam, rhopimplefoam

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Divergence in compressible LES, rhoPimpleFoam Chris B. OpenFOAM Running, Solving & CFD 13 July 6, 2021 05:07
How do you import a fully developed profile into an inlet for compressible flow? cohomology FLUENT 2 September 2, 2020 02:11
Implementing AUSM for FVM and Fully Implicit subsonic compressible flow Krishan.aero Main CFD Forum 6 December 23, 2018 23:13
Compressible rhoPimpleFoam Case Setup Help! JonathanG OpenFOAM Pre-Processing 0 July 12, 2017 11:33
Solver-guidance: Dilatable or fully compressible? Linse OpenFOAM Running, Solving & CFD 2 September 24, 2012 07:02


All times are GMT -4. The time now is 03:22.