Talk:Computational fluid dynamics/Archive 1

HYSYS is not a CFD app
HYSYS is not a CFD application. It is a steady state & dynamic process flowsheet simulator. It has a built in dynamic pipe unit (simple compressible gas model - 1 dimensional) and links to other commercial dynamic pipeline simulators (also 1 dimensional models). — Preceding unsigned comment added by Rafil (talk • contribs) 03:21, 28 September 2005 (UTC)

Contents
I fixed the contents' levels: DNS, LES etc. all under "Turbulence Methods".. — Preceding unsigned comment added by 137.138.191.73 (talk) 09:00, 09 August 2006 (UTC)

What does a typical cfd software toolchain look like?
Can anybody help me figure out the file formats and programs involved in completing cfd calculations etc.? Starting with blender, the open source 3D modeling program, I can get a mesh file (gmsh can read this), but then the majority of the cfd simulators do not seem to have a lot of documentation on how to set up a simulation (like the specifications, parameters, the types of materials, the density etc. etc.), but maybe I am missing something? And after that, how can I relate that to lift, thrust, and other properties involved in making sure, say, an airplane could fly? -- kanzure (talk) 03:04, 4 March 2008 (UTC)
 * I posted that question over at cfd-online noon earlier this day. Since then I have found that FreeFEM++ works nicely, as well as OpenFVM, and salome/OpenFOAM still questionable (though salome at least can run -- having some java environment config problems with OpenFOAM, as awesome as the whole package looks). I am stil having troubles envisioning what the entire toolchain should look like when I get it all set up. I have posted to the ff++ mailing list, the gmsh mailing list, and I am about to go write to the arocket group as well. Maybe they will have some ideas. I am surprised that this is not more thoroughly discussed on the internet yet, I suspect it is because of the perceived "math is hard" barrier. -- kanzure (talk) 03:07, 4 March 2008 (UTC)

Public CFD codes
Why only make reference to commercial codes? Why not include publicly-available codes? A list is already available in http://www-berkeley.ansys.com/cfd/CFD_codes_p.html. — Preceding unsigned comment added by 205.205.15.98 (talk) 17:42, 28 July 2004 (UTC)


 * Because we didn't know about them. Feel free to add anything you know. DJ Clayworth 13:08, 29 Jul 2004 (UTC)


 * My point was actually that it's not necessary to mention specific commercial codes, unless you plan to be exhaustive.  The idea is to not impose a commercial bias to this entry.  CFD codes started in the public domain.   I would just leave out any mention of commercial codes altogether until there are representative lists for public and commercial codes. — Preceding unsigned comment added by 205.205.15.98 (talk) 16:09, 30 July 2004 (UTC)


 * Agreed. If someone wants to make a comprehensive list, they should make a Wikipedia list article. Otherwise, codes should only be discussed if they are significant in the history or use of CFD. --Charlesreid1 (talk) 00:05, 5 November 2010 (UTC)

Why not mention commercial codes as well? It's just letting people know what's out there. (Incidentally, I'd be interested to know what you mean by "CFD codes started in the public domain". What codes do you mean? My understanding is that some CFD started in academia, but some in research labs too. Even academics might not think their work was 'public domain'.) DJ Clayworth 21:46, 30 Jul 2004 (UTC)


 * My point is that there are public and commercial codes. Why mention specifics about only one
 * of these types without mentioning the other? This is not supposed to be an advertisement page for
 * industrial interests.  You're right that many academics are using non-publicly
 * available codes, though. On the otherhand, publicly-available codes tend to come mostly from
 * academic research.
 * My point about CFD starting in the public domain is that CFD started as publicly-funded research.
 * The work by Richardson in the ... what, 20's ... was well publicised and the human algorithms
 * could easily be used by anyone who wanted to use them. Later, computer work at Los Alamos was
 * publicly, not privately, funded and published soon after. --Andy Froncioni 15:59, 7 Aug 2004 (UTC)
 * publicly, not privately, funded and published soon after. --Andy Froncioni 15:59, 7 Aug 2004 (UTC)

I have no objection whatsoever to publicly available codes being mentioned in the article. The only reason I didn't do it was that I didn't know any of them. DJ Clayworth 16:52, 9 Aug 2004 (UTC)

It's normal in Wikipedia to use lowercase for article titles except proper nouns. A lot of people write "Computational Fluid Dynamics" but we also have fluid dynamics, finite element analysis and so on. DJ Clayworth 14:01, 25 Aug 2004 (UTC)

To add to this discussion, the list of codes is getting pretty big and I'm wondering if it would help to create subcategories such as Open Source vs. Commercial Codes. These are distinct software types, unlike other subcategories such as incompressible vs. compressible codes(a lot of CFD software handles both) or solution method (e.g. Finite Element vs. Finite Difference vs. Finite Volume.)


 * To my opinion, the list has become ridiculously big and contain many things that should not be there. It seems to me that only the most relevant and generalist CFD softwares should be cited here. What is the point of a link to a "commercial CAE software for injection molding", the mesh maker should be in a mesh page etc...
 * I propose to keep only CFX, FLuent and STAR-CD for commercial codes and OpenFOAM and maybe Openflower for free codes. I am far from having an exhaustive sight of all the CFD codes, so some more cultivated CFDers of you should probably correct this list, but I really think we should drastically reduce the list. ZondeR, 28 Nov 2006


 * As I mentioned above, if someone is making a comprehensive list it should be a Wikipedia list article. The codes mentioned in the CFD article should only be those significant in the history of CFD (for example, the first commerical CFD code). --Charlesreid1 (talk) 00:07, 5 November 2010 (UTC)

Problems with the article
Why is there not any mention of LES(large eddy simulation) or DNS(direct numerical simulation) (fixed)

More importantly, what about Langrangian Techniques? Don't you think that Lagrangian and Euler based methods deserve a say in this article?

I think that there should be an introduction to the difference between the Lagrangian and Eulerian approach and how Lagrangian ones are better suited to handle interactions with rigid bodies (that are usually modelled with a Lagrangian approach). Lagrangian-Eulerian methods are also used widely in the field of CFD for computer graphics, where the main problem is the fluid-solid (and vice-versa) interaction and the free surface between the fluid and the air (that's the visible part of fluid flow, so it's important for CG). Maybe a reference to the level-set method is also needed as it is a link to this book  http://www.cambridge.org/us/catalogue/catalogue.asp?isbn=0521853109

Added 5/1/2005 I've cleaned the article up a bit, and pointed out the key issues with regard to discretization at the very beginning. User:Rtfisher

In the article it says, "While it is possible to directly solve the Navier-Stokes equations for laminar flow cases, turbulent flows require the introduction of a turbulence model."

This is not true since DNS does not use any turbulence model, although it solves the Navier-Stokes equations directly.

"Boundary conditions are defined. This involves specifying the fluid behaviour and properties at the boundaries of the problem. For transient problems, the initial conditions are also defined"

This is not true since initial conditions are specified for steady-state problems as well. In steady state problems, the solution evolves from the intial guess to the final steady state solution. — Preceding unsigned comment added by 134.117.175.33 (talk) 05:21, 17 November 2004 (UTC)


 * In that case it isn't an initial condition, it's an initial guess. By definition, initial conditions are the conditions for when the time coordinate is equal to zero.  If there is no time coordinate, there cannot be initial conditions.  So the statement is correct. --Charlesreid1 (talk) 00:10, 5 November 2010 (UTC)

There is probably no mention of LES because because nobody felt competent to write it. It's not exactly a well-known subject. I worked in the field, and I'm not competent. Feel free to add what you know. Be bold in editing. DJ Clayworth 04:00, 18 Nov 2004 (UTC)

The "Boussinesq hypothesis" link that is included under the RANS subsection should refer to Boussinesq's assumption regarding a scalar eddy viscosity and not to his approximations regarding buoyancy-driven flows. 129.22.149.57 20:38, 18 April 2007 (UTC)