# Help on SIMPLE algorithm!!

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 December 11, 2009, 05:50 Help on SIMPLE algorithm!! #1 New Member   Thiyagarajan dhayalan Join Date: Jun 2009 Posts: 7 Rep Power: 9 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.

 December 31, 2009, 04:15 SIMPLE problem #2 New Member   Prakash Ayappan Join Date: Mar 2009 Posts: 25 Rep Power: 9 I am also facing the same problem, I am anlaysis for 2D arbitary duct. Can any one help...

February 23, 2010, 02:16
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 Originally Posted by Thiyaga 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

 February 23, 2010, 06:06 #4 New Member   Join Date: Oct 2009 Posts: 29 Rep Power: 9 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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