[Nek5000-users] Specifying boundary condition for Annulus Geometry in box file

[nek5000-users at lists.mcs.anl.gov]

Hi All,

We are trying to build a mesh to simulate external cylinder flow, similar
to the one given in the example "ext_cyl". Searching though the
documentation, we understand that it is possible to generate several boxes
of mesh using genbox and combine using pretex to get the final mesh.

We are having difficulty in interpreting the boundary condition (BC)
strings in the input to files to genbox. It is clear for a rectangular box,
the BC string follows the order West, East, South, and North in 2D. What is
the analogous interpretation for a circular annulus geometry? such as for
the one defined by the box files given in "primer.pdf" (
http://www.mcs.anl.gov/~fischer/primer.pdf), which is repeated below:

x2d.rea
2 spatial dimension
1 number of fields
#
# comments
#
#
#========================================================
#
Y         cYlinder
3 -24 1     nelr,nel_theta,nelz
.5 .3         x0,y0 - center of cylinder
ccbb         descriptors: c-cyl, o-oct, b-box (1 character + space)
.5 .55 .7 .8     r0 r1 ... r_nelr
0 1 1         theta0/2pi theta1/2pi ratio
v ,W ,E ,E ,     bc's (3 characters + comma)


Does "v" corresponds to BC at r0 and W correspond to BC at r_nelr in
r-direction and the two E's correspond to BC at theta0 and theta1?

Thanks in advance for your help.

Regards,
Ravi









-- 
Ravi Kumar T R

University of Illinois at Urbana-Champaign
ph : +1 217 778 7538
http://lndvl.mechse.illinois.edu/
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