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September 16, 2010, 16:54 |
Modeling blood in CFX
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#1 |
New Member
David
Join Date: Sep 2010
Posts: 7
Rep Power: 16 |
I'm trying to model blood in CFX but I'm not sure what to do.
I tried defining it as a pure substance, but it wants a molar mass (blood of course is a mixture and does not have a molar mass). I don't know the proper amounts of components for blood to make a fixed composition mixture, and if I did I'm not sure it would end up acting as a non-newtonian fluid correctly anyway. Has anyone else modeled blood before and have any suggestions? I'm also relatively new to CFX and the rest of Ansys so I could be missing something big. Thanks! |
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September 16, 2010, 19:04 |
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#2 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,844
Rep Power: 144 |
Looks like you need to do LOTS of reading. Blood is not even close to a pure substance - it is a mixture of plasma, red and white blood cells and lots of other stuff. Does not sound pure at all to me. There is extensive literature on the fluid properties of blood, go to your uni library and start reading.
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September 17, 2010, 10:04 |
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#3 |
New Member
David
Join Date: Sep 2010
Posts: 7
Rep Power: 16 |
Yes I know it's a mixture, as I stated. And yes that's a ton of reading.
I was asking if anyone who may have already done all that reading could offer me some shortcuts on how to model it, and if I make a mixture material will it even act correctly or am I better off making an estimation with a pure substance? |
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September 17, 2010, 19:22 |
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#4 |
Member
Andy Jones
Join Date: Sep 2010
Location: Columbus, Ohio
Posts: 78
Rep Power: 16 |
Hello!
Here is a link to a Journal Article , the references may shed some light:www.cfd.com.au/cfd_conf09/PDFs/144BUI.pdf Also check out the Univ of Utah Scientific Computing Center, they are doing a lot of work on biological (anatomical) visualization and modeling :http://www.sci.utah.edu/software.html Here is a 212 pg thesis, color illustrated about cfd modeling of bloodflow. You would have to download and translate it from spanish to english, or use google translate , then save it as an english document:http://repositorium.sdum.uminho.pt/b...neiro_2009.pdf good luck! andy |
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September 17, 2010, 20:05 |
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#5 |
Member
Andy Jones
Join Date: Sep 2010
Location: Columbus, Ohio
Posts: 78
Rep Power: 16 |
Here is a 41 pg article from Stanford on modeling Bloodflow:
http://med.stanford.edu/school/vascular/Pdf/FEM-Ath.pdf And a 68pg color thesis on bloodflow modeling: http://www.stanford.edu/~anaiman/Pub...nal_Report.pdf Here is a color illustrated dissertation article on CFD modeling of blood flow. 40-50 pgs: http://www2.cs.uh.edu/~hadri/papers/...tation_phd.pdf These should give you a start and some insight on the problem and what general direction to go and what is involved. good luck! andy |
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September 17, 2010, 20:12 |
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#6 |
Member
Andy Jones
Join Date: Sep 2010
Location: Columbus, Ohio
Posts: 78
Rep Power: 16 |
Here is a 300 page article on the physical properties of blood and modeling it with respect to fluid dynamics
http://iopscience.iop.org/0034-4885/...C5041061DC3.c1 |
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September 17, 2010, 22:33 |
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#7 | |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,844
Rep Power: 144 |
Looks like Andy has been very nice to you and given you a good start to your literature review.
Quote:
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September 17, 2010, 22:35 |
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#8 |
New Member
max
Join Date: Aug 2010
Posts: 19
Rep Power: 16 |
to model blood, just make a new substance/fluid and enter these values:
3.5cp = viscosity density = 1.056grams/cm3 the toshiba stroke group at SUNY Buffalo uses these values for all of their simulations. Thats it! |
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September 20, 2010, 09:56 |
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#9 | |
New Member
David
Join Date: Sep 2010
Posts: 7
Rep Power: 16 |
Quote:
Thank you andyj. zmaxcomputer, I would still would need a value for molar mass. Maybe that's all you need in fluent, I'm not sure, but I'm using cfx. Thank you though. |
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September 20, 2010, 11:30 |
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#10 |
Senior Member
Lance
Join Date: Mar 2009
Posts: 669
Rep Power: 22 |
Have you considered the Carreau-Yasuda model? It's strain rate-dependent and have model constants that include the effects of fluid rheology (in some sense).
I don't have the expression or constants at the moment, but do a web search and you'll find it. |
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September 20, 2010, 13:21 |
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#11 | |
New Member
David
Join Date: Sep 2010
Posts: 7
Rep Power: 16 |
Quote:
I hadn't, I had tried Ostwalt de Waele before. I found a paper with parameters for Carreau-Yasuda, as well as Casson so I'm trying those out. Carreaux-Yasuda didn't come out very pretty, in fact the outlets are flowing inward but I haven't done Casson yet. This might belong in a different thread and is probably too broad or vague, but does anyone have any recommendations for fluid coming in through outlets? This has been happening frequently, whether I use Ostwalt de Waele or Carreaux-Yasuda or non-newtonian. The solver says something like "try changing boundary to Opening type" but that won't solve the problem, it would just allow fluid to come in where it's supposed to be exiting instead of making it actually exit. My boundary condition for the inlets are defining normal velocity (0.434 mm/s) and the outlets are average static pressure (0 atm, and 0.05 pres. profile blend) Thank you everybody for the help. |
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February 4, 2012, 14:26 |
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#12 |
Member
Lauren Dransfield
Join Date: Jan 2012
Posts: 50
Rep Power: 14 |
I realise this is old, but just wondering if you got anywhere with it, as I'm trying to do a CFX analysis of blood flow through the coronary artery
Any tips? |
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April 14, 2012, 17:22 |
modeling blood in artery
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#13 |
Member
Hesam Moghaddam
Join Date: Mar 2012
Posts: 49
Rep Power: 14 |
I have set up everything in CFX 13 for simulation of blood in a nasilar artery
I run the case as a transient case following the tutorial of ANSYS-CFX for a circumvent transient analysis. I run it but after the run is done and I open the results, I cannot see any specific results. Like I expect to see pressure variation on artery walls but there is just one blue color and some variation in a little part around my inlet. Any idea why I don't get any results? Thanks, Hesam |
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April 14, 2012, 17:26 |
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#14 |
Member
Lauren Dransfield
Join Date: Jan 2012
Posts: 50
Rep Power: 14 |
If you double click on the wall on the left hand panel and go through the settings at the bottom of the left panel, you should be able to change the colour from a solid to change with respect to velocity or pressure etc
If it's still blue then it's because it's using a global colour scale, right slick on your artery and in that menu or a submenu you should be able to change it to local Hope that helps |
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Tags |
blood, cfx, material properties |
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