CFD Online Logo CFD Online URL
Home > Forums > Main CFD Forum

SIMPLE for transient NS.

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

LinkBack Thread Tools Display Modes
Old   May 8, 2001, 06:46
Default SIMPLE for transient NS.
Posts: n/a
Hi, I heard that it is not recommended to apply SIMPLE-method to the transient Navier-Stokes? Why?
  Reply With Quote

Old   May 8, 2001, 12:40
Default Re: SIMPLE for transient NS.
John C. Chien
Posts: n/a
(1). For compressible flows, the methods used are normally the so-called density-based, where the continuity equation will provide one equation for the transient density calculation. (2). For incompressible flows, there is no density transient term in the continuity equation. The normal approach is to use stream function (2-D), and vorticity-velocity (3-D) formulation, where the pressure is de-coupled from the governing equations (one does not need to solve the pressure in order to solve the velocity field). (3). The pressure-based formulation like "SIMPLE" try to retain the form of primitive variable in the governing equation (instead of the derived stream function and vorticity), and solve the unknown pressure terms (in the momentum eqautions ) iteratively through another external pressure-guessing(updating) loop. And hoping that both pressure and the velocity fields will converge to the true solutions. (4). As you can see, for the transient flows, it is easier to use the compressible, density-based approach. (both explicit-marching in time, or using implicit method in time) (5). The so-called pressure-based method for transient flows will have a lot of "guessing" (iteration) to do in looking for the solution.(both the pressure and the velocity iteratively at any time)
  Reply With Quote

Old   May 10, 2001, 06:17
Default Re: SIMPLE for transient NS.
Posts: n/a
Hi, Z

Where have you heard this? Any reference? Kike
  Reply With Quote


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
SIMPLE algorithm in 3D cylindrical coordinates zouchu Main CFD Forum 1 January 20, 2014 18:02
How to add correcting pressure equation in SIMPLE of MRFSimpleFOAM? renyun0511 OpenFOAM Programming & Development 0 November 4, 2010 02:38
Making SIMPLE converge faster Fabio Main CFD Forum 4 April 9, 2006 11:35
PISO vs. SIMPLE benedikt flurl Main CFD Forum 2 April 14, 2005 06:54
flow over a 2D cyl using SIMPLE T Main CFD Forum 1 January 27, 2001 08:32

All times are GMT -4. The time now is 10:13.