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Figure 1. 

Schematic of (a) corrugated^[17] and flat-plate geometry, and (b) pitching motion.

Figure 2. 

Portions of the O-type unstructured computational mesh: (a) in the computational domain, (b) around the two airfoils, and (c) in the locally refined region near the corrugated airfoil.

Figure 3. 

(a) Variation of C_L, (b) variation of C_D, and (c) variation of surface C_P with different densities of meshes at t/T = 0.5.

Figure 4. 

Steady lift and drag coefficients at angles of attack from 5° to 10°.

Figure 5. 

Validation of lift coefficient against experimental data for (a) mild dynamic stall and (b) deep dynamic stall.

Figure 6. 

Variations of (a) lift coefficient and (b) drag coefficient with the pitching angle for corrugated and flat-plate airfoils.

Figure 7. 

Dimensionless (a) turbulent kinetic energy (TKE) and (b) spanwise vorticity ($ {\omega }_{Z} $) contours at the upstroke phase of the pitching angle.

Figure 8. 

Dimensionless velocity magnitude ($ |V|/U $) and streamline contours at the upstroke phase of the pitching angle and local enlarged view at α = 11.5°.

Figure 9. 

Vortex-core coordinates relative to the leading-edge point for the flat-plate and corrugated airfoils at different angles of attack: (a) x_core/c and (b) y_core/c.

Figure 10. 

(a) Dimensionless spanwise vorticity contours, (b) pressure coefficient contours, and (c) chordwise pressure coefficient of corrugated and flat-plate airfoils at pitching angles of 14.5° and 17.1°, respectively.

Figure 11. 

Histories of (a) C_L and (b) C_D for the corrugated and flat-plate airfoils at k = 0.02, 0.05, 0.1, and 0.2.

Figure 12. 

Dimensionless spanwise vorticity contours of the corrugated and flat-plate airfoils at (a) α = 10°, (b) 14.5°, and (c) 19.8° for k = 0.02, 0.05, 0.1, and 0.2.

Figure 13. 

Contours of (a) spanwise vorticity and (b) pressure coefficient at the peak lift for both the corrugated and flat-plate airfoils at k = 0.02, 0.05, 0.1, and 0.2.

Figure 14. 

Chordwise pressure coefficient distributions at the maximum angle (α = 20°) for the flat-plate and corrugated airfoils from k = 0.02 to 0.2 in panels (a)−(d).

Figure 15. 

Contours of dimensionless spanwise vorticity and chordwise pressure coefficient distributions at α = 19.5°, where the angle of attack approaches its maximum α = 20° during (a) upstroke and (b) downstroke phases.

Figure 16. 

Hysteresis loops of (a) lift coefficient and (b) drag coefficient for the corrugated and flat-plate airfoils at α_m1 = 10°, α_m2 = 20°, and α_m3 = 30°.

Figure 17. 

Contours of dimensionless spanwise vorticity (illustrated for [a] α = 8.5° and [b] α = 15°) for the corrugated and flat-plate airfoils at α_m1 = 10°, α_m2 = 20°, and α_m3 = 30°.

Figure 18. 

Averaged values of lift, drag, and lift-to-drag ratio for the corrugated and flat-plate airfoils under different k and ranges of α: (a) lift, (b) drag, and (c) lift-to-drag ratio.