[Nek5000-users] Representing Curved Side in any plane

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

Hi,

I was looking into the midpoint feature and generated a cube (1 element, 
x, y, z from 0 to 1) in prenek, then converted all edges to the midpoint 
notation with prenek, and then manipulated one edge in the rea file. 
This is the resulting curved side section:
   ***** CURVED SIDE DATA *****
         12 Curved sides follow IEDGE,IEL,CURVE(I),I=1,5, CCURVE
   1  1  0.500000       0.00000       0.00000       0.00000 
0.00000     m
   2  1   1.10000      0.500000       0.00000       0.00000 
0.00000     m
.
.
.
  10  1   1.00000     -0.500000      0.500000       0.00000 
0.00000     m
  11  1   1.00000       1.00000      0.500000       0.00000 
0.00000     m
  12  1   0.00000       1.00000      0.500000       0.00000 
0.00000     m

where edge 10 is supposedly not a straight line any more.

When I run this in nek, however, the cube still comes out with straight 
edges.

Are there any other parameters I need to set?

I checked out the most recent nek version and overcame compilation 
issues with gcc-gfortran 4.4.3-4.fc12 from the fedora 12 repository.

Thanks,
Markus


nek5000-users at lists.mcs.anl.gov wrote:
> 
> 
> Michael,
> 
> I've only recently added general purpose midside-node support,
> which puts a point in 3-space for any one of the 12 edges and
> nek then fits a parabola to this.
> 
> I'll set up an example that demos this.  The feature has limited
> support at the moment -- but does work in nek5000 and generates
> correct geometry.
> 
> Depending on what you are after, there may be other ways to
> generate the geometry.   One of my favorite techniques is to
> project a given input geometry onto the desired surface.
> 
> 
> Paul
> 
> 
> 
> On Sat, 27 Mar 2010, nek5000-users at lists.mcs.anl.gov wrote:
> 
> 
> 
>  Hello Users,
> 
> 
> 
> 
>  My question is in regard to the curved side data section in the REA
> file.  I know that the first 3 terms describe the side, element, and
> radius, but there are several other numbers that are currently zero, and
> then the letter C.
> 
> 
> 
>  Background for the question: I have a situation where I would like to
> curve an element edge in any plane. I know this is possible from
> previous posts regarding a sphere.rea.
> 
> 
> 
>  I know that with two points and a radius, that is enough to describe a
> circle in a plane.  But lets say I have a side where 2 pts lie on the
> XY plane, but the center of the circle is located on the YZ plane for
> example... the question is how to represent this in the REA. In the REA
> you just give the element side ( 2 pts ) and the radius, which does fix
> the circle center but the plane that contains the center is not
> fixed.  So what I am wondering is what the other numbers in this
> section do...if you could say, give the center instead of the radius, or
> give a third point with the other 2 pts in the element side to fully
> define the circle and plane.
> 
> 
> 
>  Also, Is it possible to curve the remaining 4 sides of the element
> (edges 9, 10, 11, 12 that would be in the "z" direction) in the same
> manner as edges 1-8? Thanks for any input on this matter!
> 
> 
> 
>  Regards,
> 
>  Michael Meador
> 
> 
> ------------------------------------------------------------------------
> 
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