# CFD

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 January 14, 2001, 12:57 CFD #1 John Carter Guest   Posts: n/a I am currently looking into the principles of CFD, in general. What I need is a basic understanding ( a brief overview) of what it is, and how it works. I have looked on numerous webpages etc Can anybody assist.

 January 14, 2001, 20:31 Re: CFD #2 John C. Chien Guest   Posts: n/a (1). I understand your need, but I don't have the answer right now. (2). I am almost ready to start writing a CFD/FAQ book on CD, and I hope it will answer some of your questions when it is done. I have the time right now, so be patient. (3). But I can tell you that "CFD" is "computational" + "fluid dynamics". You will need to know "fluid dynamics" part, "computational" part, and both.

 January 14, 2001, 23:37 Re: CFD #3 A. Rajani Kumar Guest   Posts: n/a You can verify CFD-ONLINE Resources part. U can find out lot of intro. and notes for CFD also. After this u can refer some good books.

 January 15, 2001, 04:16 Re: CFD #4 Apurva Shukla Guest   Posts: n/a For online information, you can also refer to http://aerodyn.org/ Please go to table of contents, their is a full chapter dedicated to computational aerodynamics, you can get a brief overview of CFD their. I hope it would help you. Regards Apurva

 January 24, 2001, 07:30 Re: CFD #5 Mukhopadhyay Guest   Posts: n/a I am, and surely others too are, waiting for your book. Congrats in advance. A story heard from a 'cfd guru': CFD -> Colored Fluid Dynamics - as some people in some industries think when they see red, green,yellow etc., vectors displayed !!

 January 24, 2001, 13:57 Re: CFD #6 John C. Chien Guest   Posts: n/a (1). The writing of the book is moving along slowly. It is a FAQ type, with many short sentenses. It is aimed at persons with no prior experience in CFD or formal training. (2). Well, like anything else in the world, the need to improve the quality comes from the consumer. I have been doing number crunching for my clients in the last several years, and I have generated a lot of color printouts. Even though, most of the calculations ran day and night, especially on the weekends, in the end, most of the results were "useless". (these were results obtained from commercial CFD codes and in-house codes) (3). I would say that, based on my experience, only less than one percent of the effort or result was useful. And in most cases, it was based on the judgement rather than the pure calculated numbers. And in most cases, the color picture itself was used to make the judgement, because the computed numbers simply were not reasonable or repeatable. That is the state of the art. (4). But if you do the CFD carefully with validation and testing, then it is possible to make the CFD results useful for that particular case. But I have to be honest with you that for anyone to obtain the right solution from a particular problem, the chance is very small. For experience expert in his own field, the chance is higher, because he knows the problem he is trying to solve, and he has the needed feeling. And that feeling is not written down , even when the paper is written and published. (5). To be able to see the right or wrong from the picture, you will need the quality very close to the god. In CFD, you can't read millions of numbers and determine whether the result is useful or not. Instead, you have to see the picture and tell whether the solution has converged or not. You also have to make decision as to whether the computed picture is physically reasonable or not. (6). Well, Color Fluid Dynamics, Yes. I would say that it is more like fortune tell palm reading, when you are trying to read the residual convergence plots. If people are out of jobs, you will see more people doing palm reading at the side walk somewhere, I guess. The world is closed, so sooner or later, it will get you, by convection and diffusion I think.

 January 24, 2001, 23:01 Re: CFD #7 Mukhopadhyay Guest   Posts: n/a Thanks a lot - we look forward to your inputs.