# Finite volume solver unstable for high Re number

 Register Blogs Members List Search Today's Posts Mark Forums Read

 October 25, 2016, 11:50 Finite volume solver unstable for high Re number #1 New Member   Sahil Gupta Join Date: Oct 2016 Posts: 4 Rep Power: 3 I am trying to solve steady state incompressible 3d lid driven cavity using SIMPLE algorithm. I have implemented CDS, FOU, SOU and QUICK schemes. I keep getting divergence for Re=400. The code converges for Re=100. Can someone tell me where might be the problem?

October 25, 2016, 13:28
#2
Senior Member

Filippo Maria Denaro
Join Date: Jul 2010
Posts: 3,673
Rep Power: 41
Quote:
 Originally Posted by sah2105 I am trying to solve steady state incompressible 3d lid driven cavity using SIMPLE algorithm. I have implemented CDS, FOU, SOU and QUICK schemes. I keep getting divergence for Re=400. The code converges for Re=100. Can someone tell me where might be the problem?

 October 26, 2016, 00:26 #3 New Member   Sahil Gupta Join Date: Oct 2016 Posts: 4 Rep Power: 3 Hi FMDenaro, Thanks for your reply. I tried refining the grid and ran simulations till 120x120x120 with no convergence. I came across some literature where the author uses third order Upwinding and has obtained results for 81x81x81. The only difference being in the formulation of equations; he has used Poisson's equation whereas I have used SIMPLE algo. Does this difference sound reasonable or is there something wrong with my code?

October 26, 2016, 00:30
#4
Senior Member

Arjun
Join Date: Mar 2009
Location: Nurenberg, Germany
Posts: 722
Rep Power: 19
Quote:
 Originally Posted by sah2105 Hi FMDenaro, Thanks for your reply. I tried refining the grid and ran simulations till 120x120x120 with no convergence. I came across some literature where the author uses third order Upwinding and has obtained results for 81x81x81. The only difference being in the formulation of equations; he has used Poisson's equation whereas I have used SIMPLE algo. Does this difference sound reasonable or is there something wrong with my code?

If your flow is incompressible then you are also solving Poisson equation in SIMPLE.
The main thing is you might be using pressure correction method while he may be using projection method.

 October 26, 2016, 00:32 #5 New Member   Sahil Gupta Join Date: Oct 2016 Posts: 4 Rep Power: 3 Yeah, you are right. So, is this discrepancy based on grid resolution possible?

 October 26, 2016, 01:43 #6 Senior Member   Filippo Maria Denaro Join Date: Jul 2010 Posts: 3,673 Rep Power: 41 Consider the fact that while the 2D case at Re=400 is steady, the 3D can not and upwind can simply add numerical viscosity and makes unphysically steady the solution... Have you tried to use periodic spanwise condition to check the 2D solutions up to Re=1000?

 November 26, 2016, 01:10 #7 New Member   Sahil Gupta Join Date: Oct 2016 Posts: 4 Rep Power: 3 Hi FMDenaro Sorry for this late reply, I was busy with my coursework. I tried out your suggestion and it worked out. The QUICK solver for 3d lid driven with periodic spanwise condition is working well for Re=400 (50x50x50 grid) and Re=1000 (100x100x100). Should I try changing my discretization scheme or add some term to decrease artificial dissipation for the 3D case?

 November 26, 2016, 03:27 #8 Senior Member   Filippo Maria Denaro Join Date: Jul 2010 Posts: 3,673 Rep Power: 41 You can try the QUICKEST and refine the grid in the confined 3D case

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post almir OpenFOAM Running, Solving & CFD 83 July 22, 2017 08:26 xoitx OpenFOAM Running, Solving & CFD 14 March 25, 2016 08:09 avinashjagdale OpenFOAM Native Meshers: snappyHexMesh and Others 50 March 7, 2016 03:35 thomasnwalshiii OpenFOAM Meshing & Mesh Conversion 18 December 19, 2015 19:57 aylalisa OpenFOAM Installation 23 June 15, 2015 14:49

All times are GMT -4. The time now is 10:44.