# What happens by doing Bandwidth Reduction?

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 January 29, 2010, 12:50 What happens by doing Bandwidth Reduction? #1 Member   Join Date: Jan 2010 Posts: 53 Rep Power: 9 Hey friends, In fluent, what happens when u do bandwidth reduction by grid>reorder>domain Why and when do u do it? Thanks

 January 30, 2010, 13:52 #2 Senior Member   Join Date: Nov 2009 Posts: 411 Rep Power: 12 After you read your mesh in Fluent you can do the bandwidth reduction. Basically Fluent will renumber the nodes of your mesh in order to have a "more diagonal" array. This will allow you to use less memory and also the solution will converge faster. Do

 January 31, 2010, 06:25 #3 Member   Join Date: Jan 2010 Posts: 53 Rep Power: 9 Hey DoHander, So basically, it means that one should make it a practice to always do bandwidth reduction after reading any mesh into Fluent...

 January 31, 2010, 13:54 #4 Senior Member   Join Date: Nov 2009 Posts: 411 Rep Power: 12 If you use any of the implicit solvers of Fluent yes, you should always do the bandwidth reduction. For the explicit solver this is useless. Do

 February 1, 2010, 12:26 #5 Member   Join Date: Jan 2010 Posts: 53 Rep Power: 9 Thanks DoHander

 February 28, 2013, 06:24 #6 New Member   Daan de Boer Join Date: Jun 2012 Posts: 6 Rep Power: 0 I also have a question on this, till what value you need to reorder to achieve the most optimal bandwidth? Seem to me that the lower the bandwidth value the better?

April 15, 2014, 02:32
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 Originally Posted by daandb I also have a question on this, till what value you need to reorder to achieve the most optimal bandwidth? Seem to me that the lower the bandwidth value the better?
Yup, lower the bandwidth value the better the solution will get in terms of solution time!! But you cannot control the value to which the bandwidth (of matrix) can be reduced, as it depends on the number of non-zero entries in the matrix(the matrix generated as the fluent solves the N-S equations)

 July 19, 2014, 05:59 #8 Super Moderator   Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,352 Blog Entries: 6 Rep Power: 45 details can be found here... http://en.wikipedia.org/wiki/Banded_matrix This also clearly shows why you cannot have advantage of reordering for explicit solver... jotac likes this.

 July 19, 2014, 06:05 #9 Super Moderator   Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,352 Blog Entries: 6 Rep Power: 45 details can be found here... http://en.wikipedia.org/wiki/Banded_matrix This also clearly shows why you cannot have advantage of reordering for explicit solver...

 Tags bandwidth reduction, fluent, reorder

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