CFD Online Discussion Forums

CFD Online Discussion Forums (
-   Main CFD Forum (
-   -   Tunnnel Simulations? (

Heinz Wilkening August 30, 1999 10:33

Tunnnel Simulations?
Ciao everybody,

I wonder if there are CFD-codes (commercial or research) around, which are able to predict the flowfield in a street tunnel including trafic such as cars or trains and ventilation. Important would be to model also the differents between having independent tubes per direction or just one tube for both directions. What would be the best way to model moving cars in a tunnel?

The subject has some importance after major accidents in european street tunnels.

Thank you!

Ciao Heinz

John C. Chien August 30, 1999 12:50

Re: Tunnnel Simulations?
(1). I don't think there are codes available which are able to predict the flow field in a tunnel..... (2). But I have seen papers which deal with flow through tunnel including exhaust gas problem using various approaches many years ago. (3). Don't worry about cars in a tunnel, cars are being replaced by SUV, and then trucks. Eventually, everyone will be driving a tank. If a German made car can not save a princess, a tank should do the job. (4). As long as there are well-trained CFD engineers and researchers, the problem can be solved. (5). I have heard about the grid-less CFD methods, and I think, pretty soon, there will be code-less CFD approaches. In the code-less CFD approach, the users simply input the information and select the answer.

Joern Beilke August 30, 1999 13:28

Re: Tunnnel Simulations?
Things like this have been done in the past with subway stations including moving trains using starcd. So I don't know why it should not work for car tunnels. Maybe there is a different physics working :) I don't know why John is that pessimistic about this case?

Sung-Eun Kim August 30, 1999 13:57

Re: Tunnnel Simulations?
I know some of our clients have been using sliding mesh capability in FLUENT (e.g., Rampant and UNS) to model trains in tunnels.

Jim Park August 30, 1999 15:27

Re: Tunnnel Simulations?
I have seen CFX simulations of trains passing in tunnels, and they recently published a short story (in their newsletter) on subway fire ventilation based on work using CFX by ICF Kaiser Engineers Inc.

Also, Flow-3D has a moving obstacle capability that should allow the simulation of two vehicles passing in a tunnel.

Both CFX and Flow Science (Flow-3D) are sponsers of this site.

Good Luck!

Greg Failla August 30, 1999 15:29

Re: Tunnnel Simulations?
I know of a paper performed using STAR-CD. "CFD Analysis of a Decelerating Train Entering an Underground Station"-Fred Mendoca (Computational Dynamics, Ltd. and Simon Drake (London Underground Ltd.). The analysis was performed using among other things, the transient arbitrary sliding interface capability in STAR-CD. Please feel free to contact me if you would like a copy.

dale T. August 30, 1999 16:31

Re: Tunnnel Simulations?
please keep your promise to be away if you can not provide useful help

John C. Chien August 30, 1999 17:25

Re: Tunnnel Simulations?
(1). It is surprised that people trust what they read on the electronic screen. (2). When I was away, I was busy checking out this efficient commercial CFD code. In the end, I was surprised, I found another big error in the output of this great commercial CFD code. (3). In the last three years alone, the three popular commercial CFD codes I have used all have serious errors in it. It would be crazy to trust anything about the commercial CFD codes. So far, I have not identified any names yet, because I don't think I can provide any useful help here to anyone who thinks that there is this great commercial CFD code ready to solve his problem.(4). Can the commercial CFD codes developers and lovers keep their promise to provide error-free codes?

John C. Chien August 30, 1999 17:49

Re: Tunnnel Simulations?
(1). The opening statement was " I wonder if there are CFD-codes(commercial or research) around, which are able to predict the flow field....." (2). Do you understand English? It is like saying " Are there word processors around which can write a report for me? " (3). In the way the question was stated, human being simply does not exist at all. (4). The question should be " Has anyone solved this type of tunnel related problems? If it is possible, is the used of a commercial CFD code necessary?" (5). People in the commercial CFD codes think that they must have the emotional reaction while the code is being evaluated. (6). Code is a code. It does not have any feeling at all. If a code is bad, it is bad. Just throw it away. The real truth is that, a code is not a code. A code is someone's expression of his ideas. And the code itself does not know how to solve the problem of even formulate the problem, but people do! (7). I am very surprised that these questions are asked by people, not by the commercial CFD codes.

Dr. Hrvoje Jasak August 31, 1999 04:17

Re: Tunnnel Simulations?

One of STAR-CD tutorials deals with the problem of two trains getting past each other (with moving mesh). Also, a commercial company (don't know which) has done the analysis of the ventilation and fire control system for the Jubilee Line Extension (London England), including moving trains, underground stations and ventilation system. Look up the paper that Greg suggested - I think this is just the thing for you.

A few more (cynical) comments to Mr. John C. Chien: 1) Well done, mate, you're thi first person on the planet with a bug-free CFD code (of, I guess, about 200k lines). Maybe you should sell it and make a fortune! 2) Some commercial codes are actually involved with things you see around you every day, so take my advice and: a) stay out of airplanes; b) stay out of cars; c) underground is a big no-no; d) I'd think twice before switching that computer on (ventilation); e) stop breathing, air-conditioning is screwy; f) lawn-mowers have engines and therefore are unsafe; g) electicity? uh-oh; h) even the vegetables (not to mention beer) in your fridge are not safe!! The best thing is to take a dive in the pool and relax... but even your swimming goggles are designed for minimum drag!

MAtej Forman August 31, 1999 04:49

Re: Tunnnel Simulations?
It is not my field, but my colleagues are working with STAR-CD and their own subroutines which simulates rows of cars by sources of momentum, turb. energy and exhausts too. They validate it with a mesurements in street canyons. Some papers should be somewhere too. That's just what I know. Have a nice rest of this summer. Matej

Joern Beilke August 31, 1999 06:39

Re: Tunnnel Simulations?
An mpeg of this tutorial is on my home page

It shows the velocity magnitude. Have some fun and a nice day.

I hope that the people from Computational Dynamics won't kill me therefor :)

John C. Chien August 31, 1999 09:29

Re: Tunnnel Simulations?
(1). Great ideas!!! (2). How come I am not getting all of these outputs from the commercial CFD codes I use? (3). Which CFD code are you using to generate these ideas? (4). For only two digits, there is a huge million dollar market created for this thing called "Y2K". I am sure that a 200k lines commercial CFD code will create more than just a million dollar new market. I think, it is more profitable to work in this "CFD Y2K" field. (In a way, I got paid well to use commercial CFD codes to find errors. )

Addy Honoho August 31, 1999 09:46

Re: Tunnnel Simulations?
1):It is more helpful 2):if you list what you found in the codes 3):instead of how great you are. 4):People who are using those codes 5):can be aware of the errors in their practice.

dale T August 31, 1999 11:10

Re: Tunnnel Simulations?
yes, he is very annoying again.

dale T August 31, 1999 11:45

Re: Tunnnel Simulations?
Thank you Dr. Hrvoje Jasak for speaking up and giving good help to serious people on this board, and the suggestion to Jonh C. Chien. We need more people like you to give ideas which make technical sense to others and to benefit all readers. Thank you again for your posting.

John C. Chien August 31, 1999 11:47

Re: Tunnnel Simulations?
(1). Don't you think that is the only purpose of the forum? (2). The great secret is to keep the secret of the code from the users ( a black box). (3). The greatest secret is to keep the secret of the secret away from the code vendors. (4). Why would a company spend a lot of money looking for problems in CFD codes? So they can find out how to build a better product. (5). So, both sides are not going to reveal their secrets to anyone. Not the vendor, not the user companies. (6). By the way, the use of a specific commercial CFD code in a company is a political decision ( not based on the accuracy of the results). You simply don't go to the engineers of a company and ask him to buy a commercial CFD license. Even the decision to use a common product like a CAD program in a company has been a multi-national strategic policy implementation. (as a result, engineers were forced to re-learn new codes from time to time. A waste of time.) (7). I like your response. A computer program can not understand the word like " annoying". A computer program can only say, " floating point over-flow", " ERROR message: xyz", and at best, something like " NOT COMPUTING !". It is not just annoying, the CFD in a company is already a global war already for sometimes.(this year, the s-brand program is out, and the t-brand program is in. Sorry, you can only do the benchmark testing when it is in the company's computer system. Contrary to our suggestions here. You can't cry in business world though.)

dale T August 31, 1999 11:55

Re: Tunnnel Simulations?
read your own msg on Aug 20. Don't wast other's time by reading your garbage. It is expensive to post here like you said. If you want to attack anyone, go to their e-mail. I have my e-mail address here too. You are way too annoying.

John C. Chien August 31, 1999 12:24

Re: Tunnnel Simulations?
(1). Frankly speaking, most large company users are aware of the problems in the commercial CFD codes. (2). But, everyone would rather cover it up and continue their CFD business as usual. (3). Unless, you are the one who is paying for the license fee out of your pocket. Most CFD engineers don't have that kind of money.(4). You don't want to know the dark side of the commercial CFD codes, do you ? (5).The answer to your question is : take a systematic approach, learn how to use a commercial CFD code. It is like some sort of "defensive-driving". In this way, the vendors and the engineering users will be happy. The vendors gets their profit, and the users get the toy to play with. (6). Who cares about the company paying the license fee? Noboby. Investors are only interested in the stoke price. They don't care whether there are bugs in the programs. And an experienced CFD engineer by definition, is the one who knows a lot about the bugs in the commercial CFD codes. So, he can get the job done faster without getting the error messages. (you can always find out these common errors in person, but not in public.)

Addy Honoho August 31, 1999 12:27

Re: Tunnnel Simulations?
You said nothing but showing yourself off.

All times are GMT -4. The time now is 21:36.