Abstract
Effects of cross cylinders placed either the upwind or the downwind sides of two parallel cylinders were examined for various pitches and positions of the cross cylinders. With cross cylinders placed downwind, aerodynamics sound becomes weaker with decreasing cross cylinders pitch. But placed upwind, aerodynamics sound doesn't change essentially. Measurements of the mean velocity field show that cross cylinders tend to elongate recirculation region of the upstream cylinder and to make the point of vortex roll up backward.
