Abstract
This study aims to investigate drag reduction of a square prism with cut-corners for nonzero values of the angle of attack
α. Selected cutout dimensions are mainly (i)
c1/
a =
c2/
a = 0.00, (ii)
c1/
a = 0.15 and
c2/
a = 0.05 and (iii)
c1/
a = 0.15 and
c2/
a = 0.25. The flow patterns are visualized by using a vortex particle method for
Re = 200, and experimentally a hydrogen-bubble (for
Re = 4000) and an oil-flow (for
Re = 10000) techniques. In addition, the hydrodynamic force on the prism is experimentally measured with either a digital manometer (for pressure coefficient
Cp) or a force transducer (for drag and lift coefficients
CD and
CL).Results for some kinds of flow patterns and the measured hydrodynamic coefficients were given with respect to the angle of attack
α. Within the present conditions, the cutout dimension of (iii)
c1/
a = 0.15 and
c2/
a = 0.25 achieves the effective drag reduction in the range 0°
α 
14° although this dimension unfortunately causes the oscillation of the gallop at about
α = 10°.
