# Output Boundary in Simple Method

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

 January 24, 2004, 09:51 Output Boundary in Simple Method #1 Yoshi Guest   Posts: n/a In the Versteeg Book titled Computatiomal Fluid Dynamics,page 197,and page 198, There is the explanation on the special treatment against the Output boundary condition in the Simple Method. If there is boundary at the (NI,J) position, To make all variable(except pressure) zero, We make UniCj=Uni-1,j But,during the iteration cycles of the SIMPLE algorithm there is no gurantee these velocity will conserve mass over thecpmputational domain as awhole. So,we must make Uni,j= Uni-1,jxMin/Mout ......... ------------------------------- I can not understand the reason why there is no gurantee these velocity will conserve mass over thecpmputational domain as awhole only making UniCj=Uni-1,j. Onother question is, If we make Uni,j= (Uni-1,j)X Min/Mout, (Min is inflow mass and Mout is outflow mass) The wake status after the obstale is drasticaly changed compared with real physical model even if the obstacle is not located at near the Output boundary.

 January 27, 2004, 08:58 Re: Output Boundary in Simple Method #3 Yoshi Guest   Posts: n/a Dear Hrvoje Jasak , Thank you for your clear explanation on my quetion. I have still 2 questions on this issue. No1. If we have 1.0 meter sized cube domain. and have same size of rectangle shaped inlet and outlet at East and West with the same size and same location at each side. If we asign 1.0 meter/sec air speed at West inlet. According to the continuity equetion rule, we get 1.0 meter/sec at the East outlet. Is this a realistic flow as the CFD result ? No 2. If we have obstacle such as 0.3 meter sized cube at the center of domain, we should have a wake with turbulence at the back side of the cube. But ,we will get no wake at the backside of cube after the extapolation on the outlet flux. Regards, Yoshi

 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 aiqch Main CFD Forum 0 April 3, 2010 16:29 IoSa CFX 1 September 14, 2006 04:48 Mark CFX 6 November 15, 2004 16:55 Yoshi Main CFD Forum 1 March 22, 2004 11:56 Deepak Main CFD Forum 1 February 25, 2004 10:48

All times are GMT -4. The time now is 19:07.