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June 16, 2009, 15:36 |
Two-Phase Condensation Case
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#1 |
Senior Member
Join Date: Jun 2009
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Please help me completing the pre-processing step for this simple case.
(**) No total temperature input is available. (***) No idea what size of droplets I have to put, because it is continuous fluid in reality. With those combinations the solution collapses. Could you allow me to get any hints to overcome troubles? I do not think CFX-v11 cannot handle such a simple two-phase calculation. Many thanks in advance. |
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June 16, 2009, 16:15 |
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#2 |
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George
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Location: Birmingham, UK
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0) what do you want to do?
1) read the manual especialy on boundary conditions choices and code stability 2) switch the input BC for massflow and output BC for static pressure to get you started
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Top 4 tips 1. Knowledge is everything and Ignorance is dangerous. 2. Understand your limitations and try to eliminate them. 3. Get yerself a bike and hoon the chuffer. You will soon learn why dogs like to hang their heads out the car window. 4. Please before asking any questions on how to run simulations in CFX, go though all the tutorials |
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June 16, 2009, 19:41 |
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#3 |
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Glenn Horrocks
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"Simple two-phase calculation"???!!! I don't think so! You are actually doing quite a difficult simulation and it does not surprise me you are having convergence problems. Condensation is a tricky process to model at the best of times.
You might want to consider using a Homogeneous Binary Mixture. Providing the phase change stuff can be treated as equilibrium this does a pretty good job of handling simple phase change. Is this approach valid for you? If your condensation is non-equilibrium then you can't use it. Whatever approach you use I guarantee it is going to be tricky to get working. Start simply with single phase flows and add the physical models one at a time making sure everything works before adding the next bit. Glenn Horrocks |
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June 17, 2009, 09:42 |
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#4 |
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ghorrocks :
I appreciate your comments to let me realize my case is challenging. I will follow your suggestion, and if it doesn't work I will have to ask FLUENT people if FLUENT can solve the case. ckleanth : You seem to think I am trying to get gold without any effort. If you carefully look into details of CFX manuals for multi-phase parts, you will come to know how poor they are with providing insufficient knowledge. |
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June 17, 2009, 10:04 |
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#5 |
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George
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not at all, its just as if you set the pressure on the outlet you have more chances to converge at that pressure. as for he manuals ; however I do quite like cfx and in many ways i think its better and more versatile than fluent.
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Top 4 tips 1. Knowledge is everything and Ignorance is dangerous. 2. Understand your limitations and try to eliminate them. 3. Get yerself a bike and hoon the chuffer. You will soon learn why dogs like to hang their heads out the car window. 4. Please before asking any questions on how to run simulations in CFX, go though all the tutorials |
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January 7, 2011, 03:22 |
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#6 |
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I encountered the same problem,
I do not kown how to define the meterial of steam and water ? using constant propertity or using IAPWS Equation of State? and using Thermal Phase Change,how to define Saturation Temperature? thanks in advance!!! |
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September 22, 2011, 06:30 |
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#7 |
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zhang
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turbo:
have you workd out this difficult simulation? |
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June 4, 2012, 00:12 |
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#8 | |
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Song Wenyu
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Quote:
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April 22, 2013, 23:16 |
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#9 | |
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Many thanks in advance! |
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April 22, 2013, 23:29 |
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#10 |
Super Moderator
Glenn Horrocks
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I do not understand your question. Can you say it again more clearly?
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April 24, 2013, 08:00 |
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#11 |
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April 24, 2013, 08:13 |
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#12 |
Super Moderator
Glenn Horrocks
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CFX has the IAPWS water properties model built in so it has all the water material properties (including subcooled/superheated regions). It will be a multiphase model with phase change so a challenge at the best of times but it should be possible. But the devil is in the detail - exactly how are you mixing it and what results are you looking for?
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May 2, 2013, 21:48 |
Sorry for replying so late
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#13 | |
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