CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Main CFD Forum

Continuity Equation

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

Reply
 
LinkBack Thread Tools Display Modes
Old   July 17, 2008, 11:56
Default Continuity Equation
  #1
Fernando Herrera
Guest
 
Posts: n/a
I need some help to understand how to use the continuity equation for the solution of a system where the density and the velocity changes all the time.

Im working on the simulation of a Downdraft gasifier. My partial differential equations include the mass balance per component in a solid fase and a gas fase, the energy balance and the momentum equation in two dimensions.

In my algorithm the idea is to solve the velocity profile first, then calculate the concentration and temperature using multigrid and then correct the velocity again.

The issue is that I don't know where to include the continuity equation.

Any ideas??

  Reply With Quote

Old   July 17, 2008, 14:31
Default Re: Continuity Equation
  #2
Paolo Lampitella
Guest
 
Posts: n/a
This is what actually CFD does and maybe you should first try to read some book before post such a question.

A simple, maybe not working, idea could be that of explicitly integrate every equation and so the continuity will give you an equation for the density. In a multiphase flow, with n components, n equations (one per phase) must be included. But there are a lot of issue connected with the time and mesh size and with your case.

Actually, in general, in compressible solvers the continuity equation is used to compute the density; in incompressible solvers it's used to derive a pressure correction equation that will force the velocity to a divergence free one
  Reply With Quote

Old   July 18, 2008, 10:11
Default Re: Continuity Equation
  #3
Fernando Herrera
Guest
 
Posts: n/a
And how do you change the continuity equation to compute the density?
  Reply With Quote

Old   July 18, 2008, 13:41
Default Re: Continuity Equation
  #4
Ramesh. K
Guest
 
Posts: n/a
Hi, I did not understand what exactly u want but if u see at the continuity equation it is partial difference equation which means that the quantities are the change with respect to the parameters even in the discretized form so when u write are solve an pde it essentially means that u are solving the changed quantities

hope u understand
  Reply With Quote

Reply

Thread Tools
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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
How to write k and epsilon before the abnormal end xiuying OpenFOAM Running, Solving & CFD 8 August 27, 2013 15:33
Upgraded from Karmic Koala 9.10 to Lucid Lynx10.04.3 bookie56 OpenFOAM Installation 8 August 13, 2011 04:03
IcoFoam parallel woes msrinath80 OpenFOAM Running, Solving & CFD 9 July 22, 2007 02:58
continuity equation Rafal Main CFD Forum 4 November 29, 2006 10:27
Could anybody help me see this error and give help liugx212 OpenFOAM Running, Solving & CFD 3 January 4, 2006 19:07


All times are GMT -4. The time now is 19:33.