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-   -   Help on SIMPLE algorithm!! (http://www.cfd-online.com/Forums/main/70983-help-simple-algorithm.html)

 Thiyaga December 11, 2009 05:50

Help on SIMPLE algorithm!!

Hi all,
i have written a code for SIMPLE algorithm in a pipe flow in a 2d domain.at the inlet i specify u velocity and at outlet iam specifying outflow i.e gradient velocity is zero(du/dx=0).I didn't specify any presssure boundary condition.Upon solving iam getting uniform u velocity and zero pressure value everywhere.Any suggestions.thanks for ur time
reg
Thiyaga.

 technocrat.prakash December 31, 2009 04:15

SIMPLE problem

I am also facing the same problem, I am anlaysis for 2D arbitary duct.

Can any one help...

 prashant810 February 23, 2010 02:16

Quote:
 Originally Posted by Thiyaga (Post 239610) Hi all, i have written a code for SIMPLE algorithm in a pipe flow in a 2d domain.at the inlet i specify u velocity and at outlet iam specifying outflow i.e gradient velocity is zero(du/dx=0).I didn't specify any presssure boundary condition.Upon solving iam getting uniform u velocity and zero pressure value everywhere.Any suggestions.thanks for ur time reg Thiyaga.
please send the code to me

 taw February 23, 2010 06:06

Hi,

I don't think SIMPLE is enough for internal / duct flow. Global mass flow may not be conserved even if cell wise the flow is divergence free. I think this is the same reason why one can't exactly get an agreement with the analytical Blasius profile and the profile obtained with SIMPLE like algorithms. Internal flow / or stream wise dominant flow should be modeled as Parabolic PDE, if you are interested in getting the fully developed laminar profiles. I read in Patankar book, in one of the last three chapters, that SIMPLER should be used instead for one direction dominant flow. Further, if you are efficient in writing codes you may include a secant procedure to preserve global mass conservation.

read for instance this paper.

www.asu.edu/courses/che331/cfd_code.pdf

the paper is written for education journal but follow the refernces to further see the issues I raised.

By the way if what I said is wrong, someone explain it to me and I would retract what I wrote above.

Cheers

TAW

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