CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Running, Solving & CFD

Converged solution with high residuals

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   November 18, 2021, 08:01
Default Converged solution with high residuals
  #1
New Member
 
Tommaso Negosanti
Join Date: Oct 2021
Posts: 7
Rep Power: 4
tommynego95 is on a distinguished road
Hi all,

I'm currently working on my final thesis job that involves a flow through a motorbike radiator.
I'm simulating a 2D section of the motorbike in exam via pimpleFoam solver but i encountered a problem.
Looking at the residuals they are actually pretty high but constant, especially the pressure one, which i'm scared of since it could compromise the physics accuracy of the solutions.
I put a probe in the geometry wake zone to control the pressure and the velocity and those values seems to be converged too since they do not oscillate neither vary in time.
As schemes, i started the simulation using
ddtscheme: Crank-Nicholson 0.5
grad scheme: cellLimited Gauss linear 1.0 for all the variables
div scheme: upwind discretization

and then, when the oscillation stopped i transitioned to
ddt: Crank-Nicolson 1.0
grad scheme: cellLimited Gauss lienar 0.5
div scheme: Gauss limitedLinear 1

that's to improve my final solution with a 2nd order discretization.
I'd like to specify that i defined also all the relaxation factors to 0.1.
As mesh, i've used snappyHexMesh that i then extruded via extrudeMesh to a 2D mesh to force a 2D simulation.
Also, the mesh present a non-orthogonality of about 46 so it should be pretty good.

Boundary conditions are pretty standard.
I' ve an inlet on the far left with a velocity Ux of 1m/s
Outlet is the far-right face with a fixed pressure of 0
XZ plane at y=0 is a symmetry plane
XZ plane at the top of the y-domain the same as the outlet
All the faces on XY plane are of "empty" type

Can anyone help me on lowering my residuals, especially p, or have any hint i can apply at my case?
Attached Files
File Type: zip pictures.zip (156.0 KB, 4 views)
tommynego95 is offline   Reply With Quote

Old   November 23, 2021, 10:43
Default
  #2
New Member
 
Tommaso Negosanti
Join Date: Oct 2021
Posts: 7
Rep Power: 4
tommynego95 is on a distinguished road
Anyone can help me please?
tommynego95 is offline   Reply With Quote

Reply


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 Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
CFX converged solution input UsamaQ CFX 6 May 29, 2020 16:48
seemingly converged solution changes after restart achat FLUENT 2 September 3, 2018 03:55
solution not getting converged shulnak FLUENT 0 July 11, 2014 14:27
Misleading low Residuals long before Steady state solution is reached! lreflow OpenFOAM Running, Solving & CFD 0 August 20, 2013 06:16
Could anybody help me see this error and give help liugx212 OpenFOAM Running, Solving & CFD 3 January 4, 2006 18:07


All times are GMT -4. The time now is 01:04.