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

Numerical Simulation Validation

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   March 29, 2018, 05:23
Post Numerical Simulation Validation
  #1
New Member
 
Muhammad Shoaib
Join Date: Mar 2018
Posts: 1
Rep Power: 0
Muhammad Shoaib is on a distinguished road
Hi Everyone! I am working on ANSYS Fluent for porous media fluid flow.. I am trying to do some simple cases to know about all the possible options and their importance. I am trying to simulate multiphase horizontal flow in a 2D parallel plate (Dimensions - 2microns x 100micons). Inlet and Outlet pressures are 0 Pa. VOF model is used, interfacial tension water/oil equal to 0.03N/m and contact angle 30deg (water-wet). Initialization with 100% oil. Water is allowed to enter from inlet due to interfacial tension force only (spontaneous imbibition). Velocity vs. flow time was obtained from numerical simulation, and later compared with analytical solution.

Different mesh sizes were used, 2 microns was divided into 5, 7, 10, 11, 20 meshes. Velocity vs flow time from analytical and numerical simulation matches exactly with 7 meshes in vertical direction. Increasing number of meshes in vertical direction, explicit VOF shows high residual of continuity and interface curvature is not smooth. I also tried to use Implicit VOF, interface curvature becomes smooth but velocity simulated is lower compared to analytical as in the previous case of explicit VOF.

Can someone tell me why continuity residual is higher in case of large number of meshes in vertical direction for explicit VOF, as I was expecting the opposite? Any other help will be highly appreciated.

Thanks!
Muhammad Shoaib is offline   Reply With Quote

Old   March 30, 2018, 15:22
Default
  #2
Senior Member
 
Lucky
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 4,795
Rep Power: 56
LuckyTran has a spectacular aura aboutLuckyTran has a spectacular aura aboutLuckyTran has a spectacular aura about
Continuity residual is not scaled in a smart way. It is normalized by the worst residual in first 5 iterations. So depending your initial guess and solver settings, you can make the continuity residual be anything. I would compare something else and not the continuity residual, it is quite useless except for seeing if the solution is more-like-converging or diverging.
LuckyTran is online now   Reply With Quote

Reply

Tags
cfd validation, contact angle, continuity residual, porous flow

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
Advice on technical requirements for the HP Z840 Workstation for numerical Simulation Ferdinand Hardware 2 November 24, 2014 13:57
TimeVaryingMappedFixedValue for Direct Numerical Simulation inlet johndeas OpenFOAM 5 May 21, 2014 07:11
About numerical filtering in direct simulation? leaf Main CFD Forum 0 June 20, 2006 01:57
Questions on direct numerical simulation feng_ji_ren Main CFD Forum 3 May 5, 2003 10:10
numerical simulation of a hydrocyclone caowei Main CFD Forum 0 January 22, 2002 04:09


All times are GMT -4. The time now is 09:05.