Flow structures around an equilateral triangle arrangement of three spheres

► Flow field around a single and three spheres in equilateral triangle arrangement was measured. ► Experimental results of PIV and dye visualization for all arrangements at Re = 5000 are presented. ► Interference of the shear layers and/or wakes of the spheres occurs severely. ► More complex features of flow patterns are obtained on the spheres located downstream of the leading sphere. ► Continuous flow development of jet flow causes a high rate of fluctuations in gap and wake.