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Old   July 11, 1999, 02:32
Default Since Last June
  #1
John C. Chien
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(1). It's been over a year since last June. In last June, my son told me about this forum and ask me to take a look at it. At that time, I had been in the desert for a couple of yesrs. It was sure nice to be at home in southern California again. (2). Soon after, my son got a free Yahoo e-mail address for me. This was nice because I could communicate with people outside my home. Later, I realized that it is convenient because it does not attach to a working place permanently. I can reach my e-mail address from any locations. Now I am using Yahoo e-mail and netzero to work with cfd-online forum at night. (3). Over the one year of time, thing has changed a lot in the political world. From the death of a princess ( a very sad story), the love story of a king ( today, we call him the president), to the war in Kosovo ( a human tragedy ),the clock did not seem to slow down a bit. When I look back, I was surprised that I had posted 443 messages already here.(4). This was done when I am away from home. At work, I am still doing the same thing. The same thing which I started almost 30 years ago. Running CFD codes, debugging CFD codes, that's all. (not quite, because I also studied very hard in C++, OpenGl,...) (5). There is something new though. And it is encouraging. Last summer, there were relatively few jobs listed under CFD. I had to use different subject names to search CFD related jobs. This time, it is different. When I type in CFD in a job site, it returned at least a couple of dozen CFD jobs. Granted, some of those may require some experience, but one has to be realistic because no company is going to specifically look for an engineer without experience. In this area, I think, the world market is learning, and CFD is growing. (6). There were negative news though. For companies without dedicated CFD engineers, the situation seems going the other way, I mean, it's getting worse. In many cases, even the in-house codes are having problems because of no constant upgrade of the codes by qualified CFD engineers. The use of commercial codes also presented the same problem because of the lack of the suitable data base for the users problem. (7). Some serious problems were encountered for the products dsigned using just codes available, not based on tested experience of engineers. (8). So, after a year since last June, the name of CFD has become more visible, and I think, the brain of a CFD engineer also has gained value. (9). And I hope that by the time the next century arrives, you will be ready to face the real problem of CFD. And that will come pretty soon, because you don't have to wait till next June.
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Old   July 11, 1999, 11:50
Default Re: Since Last June
  #2
Nuray Kayakol
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A SMALL NOTE: NOWADAYS THE RATE OF CHANGE OF PRODUCTIVITY OF THE BRAIN OF A CFD ENGINEER IS DIRECTLY RELATED TO OPTIONS OF COMMERCIAL CODES IN ORDER TO QUANTIFY THE KNOWLEDGE (SOME HOW).

AT THE SAME TIME, THE RATE OF CHANGE OF CAPABILITY OF THE BRAIN OF A CFD ENGINEER CHANGES WITH ENGINEERING'S TOYS (HIGH OR LOW LEVEL PROGRAMMING LANGUAGES (FORTRAN 90, C++ & MESSAGE COMMUNICATIONS FOR PARALLEL COMPUTING (PVM, MPI, OPENMP) ACTUALLY COMPUTER TECHNOLOGY DRIVES US. WE SHOULD HAVE UP-TO-DATE BRAINS LIKE UP-TO-DATE COMPUTERS.)

RULES AND TOOLS ARE AVAILABLE FOR ENGINEERS(OR SO-CALLED COMPUTER SLAVES).

OPTIMIZE YOUR BREATH FOR YOUR SCIENTIFIC RUN.

A DISCUSSION POINT FROM AN INTERNATIONAL COMBUSTION SYMPOSIUM (MCS 1999, TURKEY):

AS WE KNOW THAT CFD CODES CAN BE USED AS DESIGN PURPOSES. IS IT THE RIGHT TIME FOR CFD TO BE USED ON-LINE FOR OPERATION OPTIMIZATION IN INDUSTRIAL APPLICATIONS?
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Old   July 11, 1999, 21:09
Default Re: Since Last June
  #3
John C. Chien
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(1). I don't think your messages are derived from the computer codes, in-house or commercial. Therefore, you still have the total control of the CFD world and the codes. (2). When I was a college student, the mechanical design was one of my major. When I graduated from college, I had opportunities to work as a designer. What I used as a tool was a bamboo slide rule. Over the last 30 years, the slide rule has disappeared. I think, it is easier to use an electronic calculator. The one I have been using is a calculator with a basic language system in it. I have been using it since late 80's. But I rarely used the Basic language part, which was the main reason why I bought it. (3). In addition to the missing slide rule, the drawing board also gradually disappear from the design department.( not completely). I think, for 3-D design, the CAD approach is much easier than the drawing board approach, not mentioning the advantages of using the CAD files in CAM part of automation. It does shorten the overall design processes a lot. (4). But remember that the essential requirement behind it is the accuracy and the reliability of the tools. The tools must be reliable in the first place, otherwise, it is not a tool at all. (5). In CFD, I don't think any one of the code developed is reliable so far. (6). I would say that, the only reliable CFD codes are codes for low Reynolds number, laminar flows. In this area, CFD results should be reliable regardless of the code you use. But then, who is interested in the low Reynolds number, laminar flow solutions? (7). From 70's to 90's, 1-D, 2-D and 3-D CFD codes have been developed and used in various stages of "design" processes. And in the good time when there are enough resources to do testing as well, these numerical solutions , in a way, have provided trend and guidelines for the final design. (8). But now, with the testings reduced or eliminated, the CFD results suddenly become questionable. This is the issue I am talking about. (9). Over the years, there were errors in the 1-D codes, 2-D codes, and not mentioning the 3-D codes. But this wasn't a problem in the past because testings were also used to get the final answer. But now, CFD codes are being pushed to the front stage to do the design work with the impression that as long as there is a CFD code, there is a design answer. This is completely wrong because none of the codes we use today is reliable. The CFD code simply can not think by itself and it can not design any product at all. (10). Now, we are back to square-one. We need engineers who can think and who can design. The CFD code available is not a plus at all. So, the problem facing the engineers is " to use or not to use a CFD code ". I don't mean that one should not touch a CFD code at all. I am trying to say," which code should we use?" (11). Apparently, it is easy to say that " as long as the customer is happy, it is all right to use a particular code". And I know , you know this approach is not going to last forever. (12). I think, there has been a big misconception about the CFD, that is, CFD is running a CFD code. Unfortunately, most CFD results obtained so far are not correct. (13). So, the most important thing for a CFD engineer to remember is that " he must understand that the CFD solution he is going to obtain is likely to be wrong, and he must be prepared to accept it and be able to get the correct result." Sounded impossible? (14). I think, it is possible, one should be able to find the correct answer from the sea of seemingly correct solution of CFD. And This is something every CFD engineer has to face in the next century. (15). Design? Design is an iterative process with the help of existing data base. The data base can be an equation, an empirical formula, a chart or a seemingly correct CFD solution. Unfortunately, no one has taught you how to design with a wrong solution. Are you able to select the right company when all the companies bids contain diffenert CFD solution data base? It is possible, only if you have the right answer already. As for the value of a CFD engineer's brain, I don't know whether it is a function of his knowledge about the codes options.
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Old   July 12, 1999, 09:38
Default Re: Since Last June
  #4
Erich F.
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Just wanted to say thanks for the over 400 posts (think I have read all of them)...

I think the upcoming year should prove interesting in many different areas. Took my son to see a WWII airshow yesterday-makes you wonder what the next generation will experience...
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