# Meaning of 'bounded' keyword in fvSchemes.

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 May 19, 2014, 11:12 Meaning of 'bounded' keyword in fvSchemes. #1 Member   Join Date: Aug 2012 Posts: 74 Rep Power: 6 Hi, == 1 == Could someone please explain what the main difference of using "bounded" keyword result in? Code: ```divSchemes { ... div(phi,U) bounded Gauss linearUpwind grad(U); ... }``` Code: ```divSchemes { ... div(phi,U) Gauss linearUpwind grad(U); ... }``` == 2 == In Table 4.10 of http://www.openfoam.org/docs/user/fvSchemes.php, it is stated that 'linearUpwind' is 'bounded'. Despite this, why do we need to add 'bounded' keyword to the scheme arguments? ==3== Many thanks in advance.

 May 19, 2014, 11:20 #2 Member   Join Date: Aug 2012 Posts: 74 Rep Power: 6 ==1== My understanding based on the tutorial cases in OF 2.2.x, 'bounded' keyword is only added when the corresponding simulation is 'steadyState'. ==2== Even if so, the main reason is absent for myself.

 June 1, 2014, 16:57 #3 Member   Join Date: Aug 2012 Posts: 74 Rep Power: 6 Hi, The following clearly explains 'bounded' keyword's meaning: http://www.openfoam.org/version2.2.0/numerics.php nanavati likes this.

June 2, 2014, 01:16
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T Chourushi
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Good Question

Quote:
 In particular, for steady-state it is necessary to use the bounded form, equivalent to fvm::div(phi, h) - fvm::Sp(fvc::div(phi), h). For transient solutions, it is usually better to implement only the fvm::div(phi, h) term.
I have few difficulties:
(1) From where this reference is taken?
(2) What if Source is zero? Then, what it is the significance of the "bounded" term?

Any better explanation for these with reference (in relation to papers or books)?

 August 22, 2014, 08:07 #5 Member   Pratik Nanavati Join Date: May 2014 Location: Munich, Germany Posts: 40 Rep Power: 5 Agree with Tushar, On the Given link they have explained, but its on quite High Note for the beginners.

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