Menu

Discussion Forum

New Discussion
Filtrer

Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

shock tube with reaction

Posted 21 mars 2011, 14:30 UTC−4 Computational Fluid Dynamics (CFD), Chemical Reaction Engineering, Studies & Solvers Version 4.1, Version 4.2 2 Replies

xpto56
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Hi!
I'm new to comsol and I need some help figuring out if this is the right platform for the job.
I'll start a new project involving a shock tube. Some where in the tube a "curtain" of particles will be dropped by an automatic mechanism. The objective is to study the particles combustion reaction kinetics as the shock front passes through them, knowing that their displacement along the tube can be neglected. Is the Chemical Reaction Engineering Module suitable for this system?? Will I have the ability to control the time step and use very small increments (maybe 10^6s or less)??

Thanks.
2 Replies Last Post 6 déc. 2011, 06:50 UTC−5
COMSOL Moderator

Hello xpto56

Your Discussion has gone 30 days without a reply. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help.

If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base.

Fabio Ferrero
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 1 déc. 2011, 04:22 UTC−5
I am trying something very similar.
Since I have a dimerisation reaction and not a combustion for the moment, I added the reaction without using the "Chemical Reaction Engineering" interface.

Since I have high velocities, I use the new "High Mach Flow" module. It is quite ok, but I have the following problems:
- if I calculate just flux (meaning I do not couple concentrations), it has sometimes overprediction of velocities and temperature of the reflected wave;
- if I couple concentrations, there are a divergence problems. I was told the "High Mach Flow" is thought for a single ideal gas, so that's probably the cause;
- I was not able to get convergence with turbulence, with or without coupling of concentrations. So I am computing laminar flows.

So I would say that at the moment the "High Mach Flow" module ist not 100% suitable for reactions and it will probably not work for combustion.

If you made some positive experience, I could send you my e-mail address for sharing infos.

Bye,
Fabio
I am trying something very similar. Since I have a dimerisation reaction and not a combustion for the moment, I added the reaction without using the "Chemical Reaction Engineering" interface. Since I have high velocities, I use the new "High Mach Flow" module. It is quite ok, but I have the following problems: - if I calculate just flux (meaning I do not couple concentrations), it has sometimes overprediction of velocities and temperature of the reflected wave; - if I couple concentrations, there are a divergence problems. I was told the "High Mach Flow" is thought for a single ideal gas, so that's probably the cause; - I was not able to get convergence with turbulence, with or without coupling of concentrations. So I am computing laminar flows. So I would say that at the moment the "High Mach Flow" module ist not 100% suitable for reactions and it will probably not work for combustion. If you made some positive experience, I could send you my e-mail address for sharing infos. Bye, Fabio
Pedro Santos
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 6 déc. 2011, 06:50 UTC−5

I am trying something very similar.
Since I have a dimerisation reaction and not a combustion for the moment, I added the reaction without using the "Chemical Reaction Engineering" interface.

Since I have high velocities, I use the new "High Mach Flow" module. It is quite ok, but I have the following problems:
- if I calculate just flux (meaning I do not couple concentrations), it has sometimes overprediction of velocities and temperature of the reflected wave;
- if I couple concentrations, there are a divergence problems. I was told the "High Mach Flow" is thought for a single ideal gas, so that's probably the cause;
- I was not able to get convergence with turbulence, with or without coupling of concentrations. So I am computing laminar flows.

So I would say that at the moment the "High Mach Flow" module ist not 100% suitable for reactions and it will probably not work for combustion.

If you made some positive experience, I could send you my e-mail address for sharing infos.

Bye,
Fabio


Hi!!

Thanks for the ingo regarding the High Mach Flow module. I haven't tried it yet because I was using the basis of the shock-tube sample available in Comsol. However I'm dealing with some divergency issues. The most noteworthy happens when I increase de amplitude of the step function (the one used to define the initial conditions of the shock-tube - the discontinuity). Did you had this type of problems??

If I have any improvement on my model I'll let you know.

Thanks.


Pedro Santos
[QUOTE] I am trying something very similar. Since I have a dimerisation reaction and not a combustion for the moment, I added the reaction without using the "Chemical Reaction Engineering" interface. Since I have high velocities, I use the new "High Mach Flow" module. It is quite ok, but I have the following problems: - if I calculate just flux (meaning I do not couple concentrations), it has sometimes overprediction of velocities and temperature of the reflected wave; - if I couple concentrations, there are a divergence problems. I was told the "High Mach Flow" is thought for a single ideal gas, so that's probably the cause; - I was not able to get convergence with turbulence, with or without coupling of concentrations. So I am computing laminar flows. So I would say that at the moment the "High Mach Flow" module ist not 100% suitable for reactions and it will probably not work for combustion. If you made some positive experience, I could send you my e-mail address for sharing infos. Bye, Fabio [/QUOTE] Hi!! Thanks for the ingo regarding the High Mach Flow module. I haven't tried it yet because I was using the basis of the shock-tube sample available in Comsol. However I'm dealing with some divergency issues. The most noteworthy happens when I increase de amplitude of the step function (the one used to define the initial conditions of the shock-tube - the discontinuity). Did you had this type of problems?? If I have any improvement on my model I'll let you know. Thanks. Pedro Santos

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.

Suggested Content