Abstract
Effects of regularly arrayed square roughness on flow resistance and turbulent characteristics in an open channel have been investigated over a completely rough-bed with uniform stainless square ribs, where their heights were 5mm and 10mm. Detailed spatial measurements of streamwise and vertical velocity fluctuations were conducted using Particle Image Velocimetry(PIV)in a vertical plane along the completely rough bed surface. Experimental results indicated that flow resistance with three-dimensional square roughness is higher than that with two-dimensional square roughness, the maximum value of flow resistance appeared in transverse spacing delta/k(transverse spacing/roughness height ratio)=1 and significant degrees of spatially regular variation in the time-averaged velocities were generated along the rough elements.
