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

Benchmarking FLOWORKS99 with experimental datas

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

Reply
 
LinkBack Thread Tools Display Modes
Old   June 15, 2000, 10:54
Default Benchmarking FLOWORKS99 with experimental datas
  #1
Anis
Guest
 
Posts: n/a
Hi everyone.

I'm actually testing a commercial CFD code (FLOWORKS99). Finite Volume Method, rectangular grid AUTOmeshing.

I'm comparing measured mass flows through engine pipes, with those computed using FLOWORKS99.

The solver used allows two computationnal alternatives : - the incompresible one, - the compressible one.

One knows that each alternative has a specific set of computationnal algorithms : one cannot use a compressible algorithm to compute a incompressible flow.

The accuracies of the computed mass flows are not satisfying with both alternatives.

MY QUESTION WICH SEEKS ANSWER(S) :

Is the fact that FLOWORKS99 allows only one of the compressible or incompresible approaches to compute a flow, while the computed field shows a mixed subsonic-transsonic-supersonic velocity field (incompressible approach) abd a totaly subsonic field (compressible approach), THE source of error or is the sofware SIMPLY unable to compute such mixed compressible-incompressible flows?

Thank.
  Reply With Quote

Old   June 15, 2000, 12:38
Default Re: Benchmarking FLOWORKS99 with experimental datas
  #2
Raza Mirza
Guest
 
Posts: n/a
"One knows that each alternative has a specific set of computationnal algorithms : one cannot use a compressible algorithm to compute a incompressible flow."

I do not think the above statement is correct. It is true that codes do have different algorithms, but typically one code (such as FLOWORKS) would have one tupe of scheme to handle both types of flows. Common schemes are variants of SIMPLE scheme of Dr. Patankar, the so-called pressure-based schemes, and some so-called density based schemes. Both have advantages over the others in certain classes of flows.

So what if the flow is compressible in some regions and incopressible in the others. Well, one GLOBAL scheme will be used to solve for compressible flow (if the user considers the compressiblity effects to be important).

As far as the results are concerned, there are many factors. The most important is the user himself who has the responsibilty of knowing the problem and the tool. But you can check one thing: try refining your mesh (I am assuming that the AUTO meshing feature does allow at least this degree of control) and see if that brings your solution any closer to your experiments. If it does, then your solutions are not grid independent and you have to try to find grid-independence of some level first. Automatic meshing, and solution-adaptive grid refinement still need human interferece, and the user has the final responsibility.
  Reply With Quote

Old   June 22, 2000, 04:19
Default FLOWORKS99 DOES ACTUALLY DEAL QUITE GOOD WITH MIXED FLOWS
  #3
Anis MAALEM
Guest
 
Posts: n/a
After several simualtions, I actually handeled FLOWORKS99 in the appropriat manner.

Consequence : ACCURATE RESULTS.

Thanks for all.
  Reply With Quote

Old   June 22, 2000, 19:47
Default Quite Good=Accurate Results ?
  #4
John C. Chien
Guest
 
Posts: n/a
(1). When do we say that the benchmark test results are "Accurate results, Quite Good"? (2). It only rasies more questions, I think.
  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
Circular miniFlume experimental amp numerical results amelia OpenFOAM Running, Solving & CFD 11 September 4, 2005 22:42
Experimental & numerical results Amy CFX 2 September 1, 2005 08:52
Looking for the experimental data COLOPOLO Main CFD Forum 2 January 29, 2004 00:38
PhD in turbulence Hans Main CFD Forum 14 October 8, 2001 03:03
Help for combustors experimental database Pankaj shukla Main CFD Forum 0 August 25, 1999 16:19


All times are GMT -4. The time now is 20:24.