|September 27, 2012, 00:20||
Outflow boundary condition for convecction-difussion problem.
Join Date: Sep 2012
Posts: 3Rep Power: 6
Hi everybody, first of all I apologize for my english, it's not my first language.
I´m making my own code in Matlab for solving a Two Energy Equation Model (Porous media NTE) but i have a doubt about how to implement an outflow boundary condition for the fluid phase.
I´m working one dimensional flow in a very simple geometry, a square, the flow is in the x-direction.
I´m using the control volume method (Finite volume).
I´m using the power law scheme.
Remembering the general form of the control volume formulation:
My confusion lies in what it's satated in th Suhas Patankar´s book:
suppose the outflow boundary is the east boundary, Patankar states tha i should set the aE coeficient of the adyacent node to zero in order to eliminate the influence of the boundary node, and then let the value of the temperature be extrapolated from the upstream values.
according to what is stated above, should i just turn the aE coefficient to zero, and eliminate it's influence on aP or keep it.? And what about the boundary nodes, should i use the same aproach or should i use an extrapolation function (second order backward difference maybe?) or just stay stuck with the general formulation.
On the other hand, if i analyze the physical interpretation (or mathemathical) of the outflow boundary condition, it reduces, to assume the normal gradients of the flow variables (including temperature) are zero. Should i make a new discretization for the boundary node considering the above statement ?
I hope somebody can help me, thanks!!!
|Thread||Thread Starter||Forum||Replies||Last Post|
|Boundary condition problem for open channel flow||Andy||CFX||9||June 11, 2016 07:20|
|How to use a solution as an inlet boundary condition in another problem in fluent||geryes||FLUENT||0||February 25, 2010 17:32|
|problem with boundary condition???||smn||CFX||5||November 24, 2009 07:37|
|convective boundary condition for outflow BC||Pang Shengyong||Main CFD Forum||1||August 24, 2007 17:21|
|a problem with Boundary condition||M Rad||Main CFD Forum||12||November 27, 1998 13:49|