[Tobermory]

A trivial question, but I could not find any reference to this online. The relaxationFactors subdictionary of fvSolution for one of the SIMPLE solver tutorial cases reads as follows:

relaxationFactors
{
equations
{
U 0.9;
".*" 0.9;
}
}

This clearly sets the factor for the U equations (first line) and all the other variables (second line). In the OpenFoam User Guide, I have seen:

equations
{
U 0.7;
"(k|omega|epsilon).*" 0.7;
}

Can anyone please explain the terminology here? What is the .* referring to? I can see how to use it, but I'd like to know what it means, rather than it being a black box. Many thanks.

[Tobermory]

Ok - solved. Section 4.2.12 of the User Guide talks about Regular Expressions, of which this is an example.

[tas38]

As you mentioned. This is detailed with the OF user guide. But for those who future reference this forum entry, here is the explanation (taken directly from OF user guide v7)...


"inlet.*" matches any word beginning inlet. . . , including inlet itself, because ‘.’
denotes “any character” and ‘*’ denotes “repeated any number of times, including 0
times”.

"(inlet|output)" matches inlet and outlet because () specified an expression
grouping and | is an OR operator.

[Tobermory]

Thanks, Troy. The one that had me scratching my head was ".*" ... I was wondering: why not just "*". But that's not the way the regexp language works. As you point out, the "." means any character (including an empty space, but not endline) and the "*" means repeated any number of times (including zero times).

I suggest reading up the page on wikipedia: it's pretty informative.

https://en.wikipedia.org/wiki/Regular_expression