Short Description of the DLR DPW4 Solar Grids

April 21, 2009
Simone Crippa; simone.crippa@dlr.de


Content: Description of DPW4_wbt_ih0_v03_coarse3.cgns, DPW4_wbt_ih0_v03_medium3.cgns, DPW4_wbt_ih0_v03_fine3.cgns grids

The CGNS formatted grids for the grid convergence study are built upon the geometry "DPW4_wbt_ih+0_v03.igs". The grid generation was performed with Solar version 13.0.  

For all grids, the meshing guidelines (version 4, November 3rd 2008) are fulfilled in all points with the exception of point 2)h)ii), i.e., wing and tail spanwise spacing at root. This was necessary to minimize the contraction of the prismatic/hexahedral layers in this critical region. For the medium grid the maximal spanwise spacing at the wing root is approx. 0.8% of the local semispan. 
Furthermore, for generating a family of grids being as "self-similar" as possible, the expansion ratio was increased for the coarse grid above the reccommended value of 1.25 (point 2)f)) to approx. 1.3. This was necessary for achieving the same total wall-normal extension of the layers on all three grids, when consistently scaling the number of layers. 


Table 1: Comparison of grid properties with gridding guidelines; first column refers to the topics in the gridding guidelines. 

Grid				coarse		medium		fine

2)a)				1.478E-3"	9.85E-4"	6.57E-4"
2)b)				3		3		3
2)c); MedGrid as reference	1/2.87		1		3.06
2)f)				1.30092		1.2		1.13498
2)j)				8		12		18



Table 2: Summary of grid properties.

Grid				coarse		medium		fine	
	
Surface points			120E3		251E3		538E3
Max. # of wall-normal layers 	30		42		60
# of points in prism/hexa layer	3.20E6		9.18E6		27.72E6
# of cells in prism/hexa layer	3.40E6		9.60E6		28.62E6
# of tetrahedral cells		4.62E6		12.26E6		37.36E6

Total # of points		3.71E6		10.86E6		33.03E6
Total # of cells		7.62E3		21.03E6		64.19E6