CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > FLUENT

Fluctuating Surface Temperatures in Heat Transfer case: advice on convergence

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   July 18, 2023, 05:27
Default Fluctuating Surface Temperatures in Heat Transfer case: advice on convergence
  #1
New Member
 
Waru
Join Date: Apr 2022
Posts: 7
Rep Power: 4
modorous is on a distinguished road
My temperature values on the geometry surface fluctuate within three degrees (74-77C) even after 6000 iterations. I am running a multi-phase (i.e. oil and air) steady-state heat transfer problem in Fluent.

My problem involves a complex metal geometry with three sides exposed to air, and an oil jet introduced from the top to cool the geometry. The remaining side (i.e. the back wall) is defined as a boundary wall with a constant heat flux of 62,000 W/m2 to simulate heat losses to the environment. All the other boundaries are defined as adiabatic. The plate has an internal power source of 70W. The oil jet inlet temperature is 40 C. Inlet is defined as a velocity inlet with an oil volume fraction of 1. The outlet is defined as a pressure outlet.

The mesh is polyhexcore (32M cells) with 10 boundary layers an orthogonal quality of 0.1 and an aspect ratio of 400. I am using the K omega SST model and my y+ value is below 1. The multiphase model is VOF Implicit with implicit body force, VOF boundary is dispersed. The residuals for continuity and K are not below 1e-3, while the other residuals are. The total heat transfer rate imbalance is 1.5%, and the mass imbalance is 0.7%.

Could there be any issues with the chosen boundary conditions, such as the constant heat flux on the back wall (62,000 W/m2 is a guessed value) or the adiabatic walls on the other sides, causing the temperature fluctuations? I can't think of any other reasons why my temperatures fluctuate like this.

Thank you in advance for your help.
modorous is offline   Reply With Quote

Reply

Tags
conjugate heat transfer, converge cfd, steady state thermal, steady state vof, temperature

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

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
OpenFOAM error Vinay Kumar V Main CFD Forum 0 February 20, 2020 09:17
Radiation in semi-transparent media with surface-to-surface model? mpeppels CFX 11 August 22, 2019 07:30
surface heat transfer coeff of wall flux rsa FLUENT 0 June 1, 2016 09:40
Surface Heat Transfer Coefficient CFD Post MJ1105 Visualization & Post-Processing 0 February 19, 2016 04:57
Difficulty In Setting Boundary Conditions Moinul Haque CFX 4 November 25, 2014 17:30


All times are GMT -4. The time now is 22:39.