decreasing computational domain
 

Hi,

I am modeling a wells turbine and I have a question.

Turbine have 6 blades.((360/6)=60 deg=angle between blades) Due to the circumferential symmetry, only one sixth of the annulus has been computed, imposing periodic boundary conditions in the tangential direction. The computational domain has been restricted in the axial direction to six chord lengths upstream and ten chord lengths downstream of the blade.

Fig. 1:
http://kanakh.com/upload/uploads/14292137881.jpg

Now, we can to decrease angle(fig. 4) until computational domain reduce. Is this work true?

For example, instead of angle of 30 deg, we use angle of 20 deg until computational domain reduce.Is this work true? With performing this work, Are solutions of analysis good in fluent?

Fig. 2:
http://kanakh.com/upload/uploads/14292136941.jpg

Fig. 3:
http://kanakh.com/upload/uploads/14292136942.jpg

Fig. 4:
http://kanakh.com/upload/uploads/14292136945.jpg

Fig. 5......((30 deg)))
http://kanakh.com/upload/uploads/14292136943.jpg

Fig. 6:
http://kanakh.com/upload/uploads/14292136944.jpg

Can no one guide?:(

If your geometry looks like the one in fig 2; then the only solution for decreasing computationals cost is your figure 3.
Indeed by apllying periodicity you can afford to compute your domain with 360/6 = 60° slice.
I you use fig. 5 with 30° slice, and you apply periodicity, then you are computing 360/30=12 blades turbine