# Problem with the use of PRISM elements in OF-2.1.1

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October 30, 2013, 13:20
Problem with the use of PRISM elements in OF-2.1.1
#1
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India
Join Date: Oct 2012
Posts: 84
Rep Power: 7
Hi,

I am doing a simple steady state simulation(simpleFoam) in single bifurcating tube using tet+prism(near the solid walls) elements. At inlet, I have specified a fully developed velocity profile.

The problem is that fully developed velocity profile gets distorted in the straight section which should not happen(as I checked it by using pure tet mesh). The distortion occurs maximum where the transition from prism layer to tet layer occurs. How can I remove this distortion?

I have created the mesh in ICEM(in fluent format) and the total height of prism layers is about 5.2% of the radius of the straight section(parent tube). My mesh contains about 1.35 million elements(which is too much for such simple geometry.). It contains about 267,115 prism elements and approx 1.1 million tet elements.

Below are the snapshots of the geometry(half geometry), inlet velocity profile and velocity profile somewhere in straight section.
Attached Images
 Inlet Velocity Profile.jpg (25.7 KB, 5 views) gemoetry.jpg (11.3 KB, 9 views) Velocity profile in the middle of straight section.jpg (26.8 KB, 5 views)

 November 1, 2013, 02:16 #2 Member   India Join Date: Oct 2012 Posts: 84 Rep Power: 7 Any thoughts? Anybody?

 November 2, 2013, 07:08 #3 Member   cosimo bianchini Join Date: Mar 2009 Location: Florence, Tuscany, Italy Posts: 88 Rep Power: 10 It is probably related to the last prism/first tetra height ratio. I think you have to redo your mesh increasing total prism layer height to or reducing tetra dimensions in the vicinity of the prism layer. Regards, Cosimo __________________ Cosimo Bianchini Ergon Research s.r.l. Via Panciatichi, 92 50127 Florence - ITALY Tel: +39 055 0763716 Mob: +39 320 9460153 e-mail: cosimo.bianchini@ergonresearch.it URL: www.ergonresearch.it

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