Skin Friction Reduction Characteristics of Nonsmooth Surfaces Inspired by the Shapes of Barchan Dunes

Table 5

Intuitive analysis of numerical simulation tests results.

Test number	A	B	C	Result
	Depth h (mm)	Angle of repose α (°)	Spacing d (mm)
1	1	1	1	28.54%
2	1	2	2	27.98%
3	1	3	3	27.82%
4	2	1	2	29.96%
5	2	2	3	28.85%
6	2	3	1	33.63%
7	3	1	3	28.63%
8	3	2	1	32.69%
9	3	3	2	31.15%
	0.84	0.87	0.95
	0.92	0.90	0.89
	0.92	0.93	0.85
	0.28	0.29	0.32
	0.31	0.30	0.30
	0.30	0.31	0.28
R	0.03	0.02	0.04
Optimal level	A2	B3	C1
Major factor	C	A	B