|June 18, 2010, 05:44||
lost of mass conservation
Join Date: Aug 2009
Posts: 24Rep Power: 9
I am doing computation under Fluent 6.3 to model blood flow in arteries.
recently, as I wasn't satisfied with my results, I decided to check my udf with a simple cylinder.
Among different tests, I set a constant pressure outlet condition directly under fluent, and by changing one udf code, to ensure that the results will be the same.
the test was done for steady case.
I have been really surprised by the results i obtained: for a pressure condition of 0 at the outlet, everything is correct, but if I set a non 0 value ( I tried with 2000, 200 and 1) the mass conservation is not respected anymore (the difference between inlet and outlet volume flow rate is in the order of 1000% at least!). I have done the same test with my patient specific mesh, containing 19 outlets and 1 inlet, and there the mass conservation is respected.
I also tested with another cylinder, with a finer mesh, and then again, the mass conservation was lost (for a pressure of 2000 at the outlet, the outlet flow rate is 2x10^3 times the inlet flow rate).
I am wondering if this can be due to the fact that, for any reason, fluent consider the fluid as compressible. I read through the manual, but couldn't find a precise way to set or unset the compressibility of the fluid, apart from selecting ideal gas in density, which i haven't done.
If you have any idea about why I have this situation and how to tackle it, that would be very appreciated.
thank you very much.
I don't understand what went through my mind, the title should be read "lost of mass conservation" instead of "lost of mass conversation" of course.
|Thread||Thread Starter||Forum||Replies||Last Post|
|lost of mass conversation||jjchristophe||FLUENT||0||June 17, 2010 08:53|
|Mass conservation problem in mixing tank multiphase simulation||rockewan||FLUENT||0||April 6, 2010 12:34|
|mass flow in is not equal to mass flow out||saii||CFX||2||September 18, 2009 08:07|
|Mass Conservation in LES||Sas||Main CFD Forum||3||July 6, 2007 10:37|
|Mass conservation||Diego Nogueira||Main CFD Forum||1||July 30, 2004 15:50|