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September 18, 2009, 23:31 |
Feasibility of a simulation...
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#1 |
Member
Jason G.
Join Date: Sep 2009
Location: St. Louis, IL
Posts: 89
Rep Power: 16 |
I have recently installed OpenFOAM-1.6, and have started going through the documentation and tutorials to learn how to use this resource. Before I invest too much time trying to learn the ropes I wanted to ask more experienced users if my plans were feasible within the realm of OpenFOAM.
I need to simulate the spray atomization of a fluid (water in these initial tests) as it is expelled from an injector at various pressures. My goal is to simulate the effect changing certain geometries of the injector has on the spray geometry. Does this sound like something I should be able to model in OpenFOAM? I do have access to Ansys, and would prefer to do any preprocessing with that if it is possible to interface my model and any mesh information from that. Thanks -Jason |
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September 19, 2009, 00:35 |
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#2 |
Senior Member
Alberto Passalacqua
Join Date: Mar 2009
Location: Ames, Iowa, United States
Posts: 1,912
Rep Power: 36 |
Hi Jason,
what kind of model do you want/need to use? VOF? Euler-Lagrange? Euler-Euler? It is usually possible to export meshes from Ansys-FLUENT to openFOAM. Best, Alberto
__________________
Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats (current status: http://albertopassalacqua.com/?p=1541) OpenQBMM - An open-source implementation of quadrature-based moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using. |
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September 19, 2009, 01:44 |
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#3 | |
Member
Jason G.
Join Date: Sep 2009
Location: St. Louis, IL
Posts: 89
Rep Power: 16 |
Quote:
I am not yet sure which model will best suit my needs, I know I will have high pressures (1,000-2,000 bar) with multiphase flow. I'm just beginning to really get started on this project and still have a lot of research and reading on the different model types. I just discovered that my university only has an Ansys license for the FLOTRAN solver within Classical Ansys and the CFX mesher within Workbench. I have been familiar with Ansys for structural analysis, and would like to do what I can with in it; but I was under the impression it would not be ideal for multiphase flow. Thanks, Jason |
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September 19, 2009, 16:51 |
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#4 |
Senior Member
Alberto Passalacqua
Join Date: Mar 2009
Location: Ames, Iowa, United States
Posts: 1,912
Rep Power: 36 |
You should be able to export from Ansys to openFOAM. Check the formats OpenFOAM can convert from and those to which Ansys can export.
__________________
Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats (current status: http://albertopassalacqua.com/?p=1541) OpenQBMM - An open-source implementation of quadrature-based moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using. |
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September 19, 2009, 17:06 |
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#5 |
Member
Jason G.
Join Date: Sep 2009
Location: St. Louis, IL
Posts: 89
Rep Power: 16 |
Thank you. Do you think that what I am attempting to accomplish is something that I should be able to represent within OpenFOAM? I am still learning the basics, but from what I have gathered I believe I will have to determine which solver will best suite my needs. From there I will have to start a new case and write the necessary files that the solver will use as an input.
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September 19, 2009, 18:03 |
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#6 |
Senior Member
Alberto Passalacqua
Join Date: Mar 2009
Location: Ames, Iowa, United States
Posts: 1,912
Rep Power: 36 |
Hi Jason,
it really depends on what model you decide to use. OpenFOAM at the moment has a good VOF and Lagrangian implementation, while the Euler-Euler approach (two-fluid/multi-fluid) is not as advanced. For high-pressure sprays in engines, I saw some work done with Lagrangian methods (or similar, like the KIVA code), but also VOF was employed for the primary atomization. Writing the solver configuration files is not that hard. You can take example from the tutorials and eventually ask on the discussion board, if you can share the details of the work. What might be more complicated is adding functionalities to the solvers, if you need to do so. In such a case, the learning curve might be long, and more considerations are necessary to decide if OpenFOAM is the right tool or not. Speaking frankly, if you plan to use OpenFOAM in the future, and it has the functionality you need (or it is not too far from that), it is probably OK to invest time at the beginning to learn how to use it. The time required, of course, depends on what background you have in CFD and numerics. If it is a "one-time" task, or you choose to use an approach for which you can find a specialized code which can work more easily for you, it is more convenient to choose accordingly and save time. Best, Alberto
__________________
Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats (current status: http://albertopassalacqua.com/?p=1541) OpenQBMM - An open-source implementation of quadrature-based moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using. |
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September 19, 2009, 19:07 |
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#7 | |
Member
Jason G.
Join Date: Sep 2009
Location: St. Louis, IL
Posts: 89
Rep Power: 16 |
Quote:
Thank you for the input. I am currently a nearing completion of my undergraduate degree in mechanical engineering and I have a stronger background in structural analysis, but I have had an interest in CFD. I may continue my education to either the masters or doctoral level, in either case I would be continuing this research that requires this simulation. My advisor was aiming to have some simulations by November, so I may need to re discus the time table. Thanks again, Jason |
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September 19, 2009, 22:43 |
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#8 | ||
Senior Member
Alberto Passalacqua
Join Date: Mar 2009
Location: Ames, Iowa, United States
Posts: 1,912
Rep Power: 36 |
Quote:
Quote:
Probably answering to the following questions will help to decide what model to use and to understand if it is available in OpenFOAM: - Do you need to study the primary atomization or can you assume an atomizer model? - Do you need to account for evaporation or other forms of mass transfer? Best, Alberto
__________________
Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats (current status: http://albertopassalacqua.com/?p=1541) OpenQBMM - An open-source implementation of quadrature-based moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using. |
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September 19, 2009, 23:12 |
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#9 | |
Member
Jason G.
Join Date: Sep 2009
Location: St. Louis, IL
Posts: 89
Rep Power: 16 |
Quote:
For these initial simulations I should be able to assume an atomizer model and no other forms of mass transfer. My primary objective is to first show the effect various changes to the injectors geometry may have on the spray geometry, and I think it may be reasonable to simplify the problem to get started. I have been attempting to run OpenFOAM through an emulator with Ubuntu installed so I didn't have to completely switch over from Windows, but after running some of the tutorials it seems my computer will not be able to handle running it through the emulator. I think my next step will be to re-install everything on a standalone version of linux, and try to learn what I can from the tutorial cases. -Jason |
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September 19, 2009, 23:41 |
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#10 | ||
Senior Member
Alberto Passalacqua
Join Date: Mar 2009
Location: Ames, Iowa, United States
Posts: 1,912
Rep Power: 36 |
Quote:
If you need to understand how the geometry influences the formation of droplets, you cannot do that, and need VOF. Quote:
If you use a 64 bit machine, I would recommend you use openSUSE 11.1 (biased suggestion, I'm involved in openSUSE community ). You'll have linux, OpenFOAM will work like a charm on it, and the desktop will also be usable (small hint: pick GNOME, since KDE 4 is not mature yet in that release), with nice additions like flash, java and other small details working out of the box also on 64 bit machines. For help on openSUSE, join the #suse channel on Freenode, they're usually friendly and helpful. Best, Alberto
__________________
Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats (current status: http://albertopassalacqua.com/?p=1541) OpenQBMM - An open-source implementation of quadrature-based moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using. |
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September 20, 2009, 00:31 |
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#11 | |
Member
Jason G.
Join Date: Sep 2009
Location: St. Louis, IL
Posts: 89
Rep Power: 16 |
Quote:
Thanks again for all the advice. -Jason |
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September 20, 2009, 02:55 |
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#12 | |
Senior Member
Alberto Passalacqua
Join Date: Mar 2009
Location: Ames, Iowa, United States
Posts: 1,912
Rep Power: 36 |
Quote:
However, yes, openSUSE has a graphical installer which is probably one of the best around in my opinion, and has surely more graphical configuration tools (YaST) than Ubuntu. You can of course re-partition your disk directly from the installer, and your Windows partition will be resized and made readable from Linux too. You can see the steps of the installation of openSUSE 11.1 from the DVD (which I recommend, if you have a fast connection, since it brings you all the tools you need in one single medium) here: http://en.opensuse.org/Installation/11.1_DVD_Install The live-cd installation is similar. The installer follows almost the same steps, but it is started from inside the live system. You can see it here for the KDE cd, but of course it is similar also for the GNOME cd: http://en.opensuse.org/Installation/11.1_Live_CD Best, Alberto
__________________
Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats (current status: http://albertopassalacqua.com/?p=1541) OpenQBMM - An open-source implementation of quadrature-based moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using. |
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September 20, 2009, 11:08 |
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#13 |
Member
Jason G.
Join Date: Sep 2009
Location: St. Louis, IL
Posts: 89
Rep Power: 16 |
Thanks! I will have to try to download the DVD when I get on campus with the better connection speeds.
-Jason |
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September 22, 2009, 17:33 |
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#14 |
Member
Jason G.
Join Date: Sep 2009
Location: St. Louis, IL
Posts: 89
Rep Power: 16 |
I received some more clarification on my roles in this project, and I will only be modeling the atomization of a diesel fuel as it is injected with a known angle and initial velocity or pressure. I will need to develop a dynamic mesh to incorporate the changing volume of a cylinder, and can initially model the lower boundary as a flat surface. I am going to start by installing OpenSUSE and re-installing OpenFOAM, as I don't think the emulator will get me much further.
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September 23, 2009, 22:03 |
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#15 |
Senior Member
Alberto Passalacqua
Join Date: Mar 2009
Location: Ames, Iowa, United States
Posts: 1,912
Rep Power: 36 |
Hi, this is good news for you, I guess, since similar work has already been done in OpenFOAM, and you should be able to find references or contact who did it.
Good luck, and ask if you have problems :-)
__________________
Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats (current status: http://albertopassalacqua.com/?p=1541) OpenQBMM - An open-source implementation of quadrature-based moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using. |
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September 23, 2009, 22:26 |
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#16 | |
Member
Jason G.
Join Date: Sep 2009
Location: St. Louis, IL
Posts: 89
Rep Power: 16 |
Quote:
Thanks! I am just having a few issues getting a full install of linux. I only have an external CD drive for my laptop, and I am running into issues with being able to boot from it... but that topic is slightly outside the scope of this forum . -Jason |
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September 29, 2009, 04:34 |
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#17 |
Senior Member
Eugene de Villiers
Join Date: Mar 2009
Posts: 725
Rep Power: 21 |
Hi Jason,
I did some VOF modelling of primary diesel spray atomisation a few years ago. If you send me you e-mail address I can forward the pdfs of the papers we published on the subject to you. Eugene PS. Not sure if you can see my e-mail address. If not, just send me your address via the forum messaging service. |
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