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May 30, 2012, 22:01 |
Patching multifluid flow
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#1 |
New Member
Join Date: Jan 2012
Posts: 11
Rep Power: 14 |
Hi all,
I am having trouble initializing my multi-fluid vof model in Fluent. I am trying to simulate a simple open channel flow over a bump for a uni assignment. My primary phase is air, and secondary phase in water. I am attempting to patch within fluent by adapt>region>mark, I then patch that region in initialization but when I view the volume fraction plot it is all the primary phase (air). Is there something im missing? Thanks |
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May 31, 2012, 04:05 |
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#2 |
Senior Member
Rick
Join Date: Oct 2010
Posts: 1,016
Rep Power: 26 |
Hi, make sure to:
- Adapt->Region.... Choose either Quad or Circle for 2D. Enter the Input Coordinates, and press Mark. - In the Patch window, a new item just appeared, something like hexaedron. select this, write inputs and patch. Daniele |
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May 31, 2012, 06:46 |
Patching multifluid flow
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#3 |
Senior Member
Vaze
Join Date: Jun 2009
Posts: 172
Rep Power: 16 |
Hi svanmunster
Also make sure following - If you mark the cells from secondary fluid side then define volume fraction 1 for secondary phase in that marked domain. otherwise reverse the situation. Regards mvee |
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May 31, 2012, 07:10 |
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#4 | |
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Quote:
Another quick question if you dont mind. When viewing the volume fraction contour plot of the flow, there are values that are not equal to 1 or 0 but rather intermediate values. Does this mean that the water is mixing with the air??? That shouldnt be happening? |
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May 31, 2012, 07:17 |
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#5 | |
Senior Member
Rick
Join Date: Oct 2010
Posts: 1,016
Rep Power: 26 |
Quote:
A quick search on forum returns an old reply of amir: Question: When I patch a small volume I get an avaraged value of the specified parameter at the marginal grid of the volume. How can I avoid it? answer: it doesn't occur if you display cell values not node values. (you can set that in display->contour) Daniele |
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May 31, 2012, 08:05 |
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#6 |
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Join Date: Jan 2012
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Can't seem to find that option. Nevermind I can live with it (as long as fluent doesnt think it is mixing). If you dont mind danielle I have a further question in regards to viewing the velocity vectors/contours. With the multi-phase fluid I only have the option to view the velocity of the 'mixture' whereas I am only interested in the velocity of the water. Is there a way around this?
Thanks again! |
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May 31, 2012, 08:52 |
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#7 |
Senior Member
Rick
Join Date: Oct 2010
Posts: 1,016
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In the display->contour (the window where you choose "contours of.." and you click "display" to see contour) deselect "node values" and you will see only 0 / 1 vapor fraction.
Either in the display->contour you shoud see the option to change from mixture to phase-1 or phase-2 (choose velocity, then change from mixture to phase-1, assuming phase-1 is water). Daniele |
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May 31, 2012, 17:54 |
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#8 |
New Member
Join Date: Jan 2012
Posts: 11
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http://img856.imageshack.us/img856/3302/cfdforum.jpg
I have uploaded a photo which shows my issues. As you can see there is no option to select anything other than 'mixture' in the drop down box. I have also unchecked node values in display but as you can see the volume fraction contour plot is still taking intermediate values. Also, I am trying to simulate a hydraulic jump do you have any idea why the flow beyond the bump is not jumping? Thanks again. |
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March 14, 2014, 11:14 |
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#9 |
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Join Date: Jan 2014
Location: Turkey
Posts: 37
Rep Power: 12 |
Hello dear friends,
I try to simulate melting process using VOF model. Pcm is solid phase initialy. Upper part of the solid there is air. They do not mix eachother. he rectangular box is %85 full with solid pcm, %15 air. Natural convection is active. My primary phase air, secondary phase is pcm (phase change material). I have some questions to be sure about my model. First, I do not define interface between air and pcm. Mean, There are 3 cell zone: air, fin ,pcm but I do not create name selection for this interface in meshing. Is it ok? Initial condition of Wholesystem temperature is 293K, but air temp is 300K. how to set air temp ? For cell zone condition, all cell zone (air, pcm, fin ) show mixture. Also for example, if I change pcm to phase2, all of cell zone change to phase 2 Only for secondary phase (pcm), I patch within fluent by adapt-region-mark then patch. Ok? Value of volume fraction should be 1 or 0 while patching?? I am confused. Initialy pcm is solid. For initial values phase-2 volume fraction is 0. Ok? I did some iteration for a short time to check model. For results, in graphics-countors I can not see total temperature for phase 1 and 2 only entalphy values I see for phase1 and 2. Also countors of solidification/melting it shows only mixture. Mixture show what? Any interaction should I use like surface tension etc. Thanks for your help. ı am really in stuck. good work friends. Last edited by thermal energy; March 15, 2014 at 07:05. |
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May 4, 2014, 12:37 |
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#10 |
New Member
Join Date: Jul 2013
Posts: 4
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can any one tell me how to plot velocity vector in multiphase??
when i m plotting it velocity of phase 1 it is not showing any thing in display but it is working with phase 2... |
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