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-   -   Meaning of 'bounded' keyword in fvSchemes. (https://www.cfd-online.com/Forums/openfoam-pre-processing/135882-meaning-bounded-keyword-fvschemes.html)

HakikiCanakkaleli May 19, 2014 11:12
Meaning of 'bounded' keyword in fvSchemes.
 
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.

HakikiCanakkaleli May 19, 2014 11:20
==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.

HakikiCanakkaleli June 1, 2014 16:57
Hi,

The following clearly explains 'bounded' keyword's meaning:

http://www.openfoam.org/version2.2.0/numerics.php

Tushar@cfd June 2, 2014 01:16
Good Question

As stated on the link:

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)?

nanavati August 22, 2014 08:07
Agree with Tushar,

On the Given link they have explained, but its on quite High Note for the beginners.


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