Hi, everyone! I have a que
 

Hi, everyone!

I have a question about syntax. In anlitycalCylinder (from tutorials) I came across next code

U.boundaryField()[3][0].x()
U.mesh().boundary()[4].Cf()[0]

What do [3][0] in the first case and [4]...[0] in the second case mean? Is it a some kind of element indexing? I've read Guides very attentively, but unfortunately there is no information at all.

Hope to get some help.

It is indeed indexing. U.bo
 

It is indeed indexing.

U.boundaryField()[3][0].x()
This is the x component of velocity for face number 0 from boundary region number 3. I.e. the first index accesses a specific boundary region of the U field, while the second addresses the face within that region.

U.mesh().boundary()[4].Cf()[0]
This is the face centre vector for face number 0 from boundary region number 4.

I was thinking something like
 

I was thinking something like that, but I wanted to be sure http://www.cfd-online.com/OpenFOAM_D...part/happy.gif

Thank you for reply