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Tadiwos October 16, 2001 05:17

air conditioning in cars
Hello CFX Friends,

I want to model air conditioning inside a small BMW car. I have two questions:

1) How much detail should I make the geometry using CFX Build? It is difficult for me to represent everything inside the car i.e, the seats, wheel drive, brakes.....

2) Is it two dimensional or three dimensional flow should I use?, I would like to get good validation results interms of temperature.

3) Is there any one who is working on such kind of research. if there is please post your address and I will try to contact you.

Thank you very much for your help.

CFX researcher

Herve October 16, 2001 07:14

Re: air conditioning in cars
Why don't you get a CAD file from your client? You can import nice CAD surfaces into Build and therefore easily include dashboard, seats windows etc...

Tadiwos October 16, 2001 07:26

Re: air conditioning in cars
Herve, thanks for your suggestion, but what do you mean by client? Do you mean the BMW manufacturer?


Herve October 16, 2001 08:18

Re: air conditioning in cars
I meant if you have been asked to carry out such work on a specific car, the person requiring the work might have the CAD file from which you can start (do an import in Build).

If not,and you are carrying the job for yourself you can implement a general shape for the cockpit and the seats in the cockpit directly in Build, bearing in mind what is important for your model (e.g. you won't need all the intricate shapes of the seat to be included) or look for any CAD file on the net from companies such as for example.

John C. Chien October 16, 2001 15:25

Re: air conditioning in cars
(1). I would suggest that you start with a simple 3-D model,with a 2-D cross-section first. (using the car symmetry plane cross-sectional shape) (2). If you can't do simple 3-D, then it is hopeless.

Fabian October 17, 2001 03:48

Re: air conditioning in cars
Herwig,H.; Klemp,K.; Schmücker,A.; Currle,J.: "Ventilation of passenger car cabins: Comparison of experimental and numerical data" Forschung im Ingenieurwesen - Engineering Research, Bd. 62, 161-167, 1996

Tadiwos October 17, 2001 04:08

Re: air conditioning in cars
Thanks guys

Fabian, can you please tell me where I can find the reference that you pointed out?


Fabian October 17, 2001 04:32

Re: air conditioning in cars

Joern Beilke October 17, 2001 04:44

Re: air conditioning in cars
To get some impression you could look at

under Examples --> Passenger Compartment

Jon October 18, 2001 05:11

Re: air conditioning in cars
Then again, you could look at the comments made under 'compare CFX5 and Star-CD' and realise that you'd be better off sticking with CFX5.

Joern Beilke October 18, 2001 08:43

Re: air conditioning in cars
good joke :)

but ist not important which tool you use but how you use it. So even that example might help to get an impression whats usually done in this area of cfd.

Jon October 18, 2001 09:31

Re: air conditioning in cars
Who's joking?



So why didn't you pass them on to the cfx website, as this is the cfx forum?

Joern Beilke October 18, 2001 11:26

Re: air conditioning in cars
I'd love to switch to CFX if it would be that superior but it is simply not powerful enough.

If you look at the examples on my home-page you will know why. It is some very simple moving mesh stuff -- nothing special and several years old.

Once CFX can handle this kind of problems we can go on talking.

Jon October 18, 2001 11:52

Re: air conditioning in cars
It can, I believe.

Joern Beilke October 18, 2001 13:04

Re: air conditioning in cars
Science is not a good place to "believe" something. Either you know it or not.

John C. Chien October 18, 2001 13:14

Re: air conditioning in cars
(1). I am getting the message that many people in CFD are very confused that they tend to think that computer codes are their gods. (2). I think, I like your message, because you are not the one who is confused.

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