# First Order to Higher Order Blending Factor

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

 September 5, 2012, 13:47 First Order to Higher Order Blending Factor #1 Member     NormalVector Join Date: Oct 2010 Posts: 72 Rep Power: 6 I'm trying to understand the discretization blending factor Fluent has available (accessible through TUI solve/set/numerics). From what I see in the Fluent users' manual, a value of 0 will use a first order discretization while a value of 1 will "recover higher order discretization." It notes that in order to use it effectively, one of the higher order schemes must be selected for the desirable variables. Does that mean that I have to use at least a second order discretization for density, momentum, etc. in order for the blending to work properly? I'm having convergence troubles at second order upwind so I'm trying to squeeze all the accuracy I can out of first order.

 April 1, 2013, 17:57 #2 Senior Member   Astio Lamar Join Date: May 2012 Location: Pipe Posts: 154 Rep Power: 5 Hi! I have the same question. Do you find any answer? Thanks.

 April 1, 2013, 18:56 #3 Member     NormalVector Join Date: Oct 2010 Posts: 72 Rep Power: 6 Nope, never did. I just pushed through second order by changing the relaxation factors.

 April 3, 2013, 15:43 #4 Senior Member   OJ Join Date: Apr 2012 Location: United Kindom Posts: 475 Rep Power: 11 Yes you do need to have a second (or higher order) solution in order to be able to use the blending factor. In very simplistic terms, blending factor B can be defined as: Here is the quantity like velocity, pressure etc. Now, if you have a look at the equation, if B=0, we have results of first order and if B=1, we have results of higher order. But if you don't have a higher order solution, then becomes , and for any value of B, you get the solution the same as . Hence it is necessary to have a second or higher order solution in order to use blending factor. It is healthy to go gradually from first order to different blending factors (0.4, 0.7) etc depending on your unstability and then switch to second order, if you are having problems with direct second order solutions. OJ asal and chengyu like this.

 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 Torque_Converter CFX 7 January 8, 2013 05:07 Emma66 FLUENT 1 April 27, 2010 05:44 Apurva Shukla Main CFD Forum 4 December 15, 2000 10:17 jianxia Main CFD Forum 0 June 6, 2000 19:40 Sergey Smirnov Main CFD Forum 10 April 15, 2000 01:49

All times are GMT -4. The time now is 20:41.