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About shock tube model

Posted Mar 23, 2010, 5:11 a.m. EDT 7 Replies

André Cordeiro
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Hi there,

I have going through the shock tube model: www.comsol.com/showroom/gallery/100/ but I found something strange: should not the pressure wave reach the boundaries (3m tube) in the order of milisenconds? In the results it shows that even after 1 second the wave have not arrive... I am missing something???

Thanks!
7 Replies Last Post Oct 1, 2012, 4:10 a.m. EDT
COMSOL Moderator

Hello André Cordeiro

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Fabio Ferrero
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Posted: 1 decade ago Dec 1, 2011, 4:33 a.m. EST
You are right. I never thought about that! Probably y is not the real time, but some dimensionless number related to time. Support should helb you with that.

Fabio
You are right. I never thought about that! Probably y is not the real time, but some dimensionless number related to time. Support should helb you with that. Fabio
Pedro Santos
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Posted: 1 decade ago Dec 13, 2011, 7:12 p.m. EST
Hi!!!
I've been going through that model also and I guess they worked with non-dimensional NS equations, although the dimensions of the geometry are marked as lenght units.
Another curiosity is that the model doesn't seem to handel with greater amplitudes on the step function. In real experiments I believe that the driver zone reaches pressures higher than twice the one of the driven zone (which usually is kept at atmosferic pressure).
Have you tried to contact the Comsol's support??

If you have any information about this model that you could share I would be very appreciated.


Pedro Santos
Hi!!! I've been going through that model also and I guess they worked with non-dimensional NS equations, although the dimensions of the geometry are marked as lenght units. Another curiosity is that the model doesn't seem to handel with greater amplitudes on the step function. In real experiments I believe that the driver zone reaches pressures higher than twice the one of the driven zone (which usually is kept at atmosferic pressure). Have you tried to contact the Comsol's support?? If you have any information about this model that you could share I would be very appreciated. Pedro Santos
Fabio Ferrero
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Posted: 1 decade ago Dec 14, 2011, 4:29 a.m. EST
Hi!!!

I tryed to use the model for other gammas (1.1), but I also have divergence problems.

I asked the support for the case of gamma 1.4 with a pressure ratio of 20/1 and they did it for me.
So I think just ask and they will solve it for you.

Bye,
Fabio
Hi!!! I tryed to use the model for other gammas (1.1), but I also have divergence problems. I asked the support for the case of gamma 1.4 with a pressure ratio of 20/1 and they did it for me. So I think just ask and they will solve it for you. Bye, Fabio
Pedro Santos
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Posted: 1 decade ago Dec 14, 2011, 5:37 a.m. EST
Hi!!

Thanks for the reply. Is to good to know that one can get result for such pressure ratios. I just wonder what were the changes they've made to the model. I've tried many things and nothing worked except for the use of a bigger domain. Could you send me the model file??

Thanks.



Pedro Santos
Hi!! Thanks for the reply. Is to good to know that one can get result for such pressure ratios. I just wonder what were the changes they've made to the model. I've tried many things and nothing worked except for the use of a bigger domain. Could you send me the model file?? Thanks. Pedro Santos
Fabio Ferrero
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Posted: 1 decade ago Dec 14, 2011, 5:50 a.m. EST
I will send you a private message with my e-mail address!
Fabio
I will send you a private message with my e-mail address! Fabio
Jian Wu
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Posted: 1 decade ago Sep 17, 2012, 9:10 a.m. EDT
Hi!

Have you solved the model with a higher pressure ratio. I met the same problem during my study, which troubled me for several weeks. could you give me some advice?

Thank you very much for the help!

Jian Wu


Hi!!!

I tryed to use the model for other gammas (1.1), but I also have divergence problems.

I asked the support for the case of gamma 1.4 with a pressure ratio of 20/1 and they did it for me.
So I think just ask and they will solve it for you.

Bye,
Fabio


Hi! Have you solved the model with a higher pressure ratio. I met the same problem during my study, which troubled me for several weeks. could you give me some advice? Thank you very much for the help! Jian Wu [QUOTE] Hi!!! I tryed to use the model for other gammas (1.1), but I also have divergence problems. I asked the support for the case of gamma 1.4 with a pressure ratio of 20/1 and they did it for me. So I think just ask and they will solve it for you. Bye, Fabio [/QUOTE]
Fabio Ferrero
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Posted: 1 decade ago Oct 1, 2012, 4:10 a.m. EDT
As I suggested, ask the support, they did it for me and I think they will do it for you!
Fabio
As I suggested, ask the support, they did it for me and I think they will do it for you! Fabio

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