# SIMPLE for transient NS.

 User Name Remember Me Password
 Register Blogs Members List Search Today's Posts Mark Forums Read

 May 8, 2001, 06:46 SIMPLE for transient NS. #1 zhor Guest   Posts: n/a Sponsored Links Hi, I heard that it is not recommended to apply SIMPLE-method to the transient Navier-Stokes? Why?

 May 8, 2001, 12:40 Re: SIMPLE for transient NS. #2 John C. Chien Guest   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)

 May 10, 2001, 06:17 Re: SIMPLE for transient NS. #3 Kike Guest   Posts: n/a Hi, Z Where have you heard this? Any reference? Kike

 Thread Tools Display Modes Linear Mode

 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 OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post zouchu Main CFD Forum 1 January 20, 2014 18:02 renyun0511 OpenFOAM Programming & Development 0 November 4, 2010 02:38 Fabio Main CFD Forum 4 April 9, 2006 11:35 benedikt flurl Main CFD Forum 2 April 14, 2005 06:54 T Main CFD Forum 1 January 27, 2001 08:32