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

Stable discretizatin scheme

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

Like Tree2Likes
  • 2 Post By einandr

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   July 1, 2013, 22:14
Default Stable discretizatin scheme
  #1
New Member
 
Patricio Javier Valades Pelayo
Join Date: Jun 2013
Posts: 5
Rep Power: 12
patovalades is on a distinguished road
Hello, could someone recommend me a discretization scheme (and the place to find it explained) that is stable, for the following:

-Solving a 2D-Unsteady state mass transfer equation on a pipe, using Cylindrical coordinates. Radial and axial spatial coordinates considered & no dependence with respect to tetha (axisymmetrical).

-Assuming the momentum equation yields a fully developed parabolic velocity profile (Laminar flow).

-Considering radial diffusion, axial diffusion and axial convection.

-Outter boundary condition no mass transfer.
patovalades is offline   Reply With Quote

Old   July 7, 2013, 05:52
Default
  #2
New Member
 
Andrey Yakovchuk
Join Date: Nov 2012
Posts: 24
Rep Power: 13
einandr is on a distinguished road
As long as you can model constant density, you need pressure-based segregated solver. Then adjust courant number to achieve stability (no more than 1 for transient flows). Look at www.bakker.org for lectures about solvers and discretisation schemes. Firstly achieve convergense on 1-order upwind then on 2-order upwind scheme for flow (for steady-state), or use 2-order upwind at once for transient problem.

You task is simple, wish you good results
And and patovalades like this.
einandr is offline   Reply With Quote

Old   July 19, 2013, 04:12
Default
  #3
And
New Member
 
Andrea Aprovitola
Join Date: Nov 2009
Posts: 16
Rep Power: 16
And is on a distinguished road
Quote:
Originally Posted by einandr View Post
As long as you can model constant density, you need pressure-based segregated solver. Then adjust courant number to achieve stability (no more than 1 for transient flows). Look at www.bakker.org for lectures about solvers and discretisation schemes. Firstly achieve convergense on 1-order upwind then on 2-order upwind scheme for flow (for steady-state), or use 2-order upwind at once for transient problem.

You task is simple, wish you good results
I agree with the adoption of a segregated solver for this problem. Moreover as you are dealing with mass transfer problem in an incompressibile laminar flow, I would try to adopt finite volume-based discretization schemes using colocated variable ( velocity and pressure defined on centroid of control volume ) rather than finite difference schemes.

You will introduce in your computation an error on the net mass flux over a control volume, at each time step, having the magnitude of the local truncation error on your grid. Hence your stability check will be based on the evaluation of the divergence of the velocity field across the flow domain which has to remain bounded and of the order of LTE. This will give you an info about the global amount of mass transfer due to the numerical procedure.
And is offline   Reply With Quote

Reply

Tags
mass balance, stability problem, unsteady state

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
Is central scheme stable for stokes flow limit ? vijay_paul Main CFD Forum 0 March 31, 2012 19:43
When to use upwind or central differencing schemes? quarkz Main CFD Forum 6 August 19, 2011 04:24
2nd order upwind scheme (Fluent and CFX) Far FLUENT 0 May 22, 2011 02:50
Looking for stable integration scheme for 2D Shallow Water Equations maddhi OpenFOAM Running, Solving & CFD 1 August 23, 2008 07:24
extrapolation in MUSCL scheme Chandra Main CFD Forum 6 February 14, 2007 12:21


All times are GMT -4. The time now is 22:12.