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-   -   Rotating mesh using newxyz.f (http://www.cfd-online.com/Forums/star-cd/72018-rotating-mesh-using-newxyz-f.html)

 Kev January 22, 2010 12:05

Rotating mesh using newxyz.f

Hello everybody,

I would like to simulate the flow in a rotating machine using subroutine newxyz.
The geometry is simple : intake pipe, outer ring, inner ring and exhaust pipe.

I have tried tutorial 7.1, 7.2 and 11.1.
None of them uses newxyz, instead they used cgrid.cgrd.
I have some question :
- is it necessary to specify events as well when using newxyz ?
- is it necessary to define attach boundaries between moving cells and non-moving cells ?
- is there an easier way to specify moving cells than knowing their vertices numbers (in newxyz) ?
- have i got to create couples between inner ring (rotating) and outer rinf (non-rotating) ?

Some help would be much appreciated,

Thanks,

Kevin

 Mike Henneke February 6, 2010 19:56

I have some question :
- is it necessary to specify events as well when using newxyz ?

In this case you need to include sliding attach boundaries between moving and stationary cells. Activating these requires events.

- is it necessary to define attach boundaries between moving cells and non-moving cells ?

Yes.

- is there an easier way to specify moving cells than knowing their vertices numbers (in newxyz) ?

You don't need vertex numbers in newxyz. What you should is to sweep through the vertices, calculate their theta coordinate, increment theta appropriately, then calculate the xyz coordinates and update the vertex coordinates.

The easier way to do this is to put the rotating cells into their own cell table and specify a 'spin' for this cell table.

- have i got to create couples between inner ring (rotating) and outer rinf (non-rotating) ?

No you need attach boundaries.

To activate the attach boundaries you'll need a series of commands like this:
evslide,1
epslide,on
eoslide,2
evsave,1
evflag,prep,on,newxyz
easi,1,enable
evprep

I'd recommend you run this analysis in Star-CCM+. It's quite a bit easier if you just want pure rotation and don't need to distort the geometry.

--Mike

 Kev February 7, 2010 08:37

Thank you Mike ;),

Since my first post, i managed to do this, using cgrid.cgrd + arbitrary sliding event.

cgrid is easier to use : star-cd commands versus fortran...

Unfortunately, i don't have star-ccm+, so i had to cope with 3.26.

Thanks again,

Kevin

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