Turbulent Flow in Very Noncircular Conduit

Measurements of the friction factor variation with Reynolds number, and the mean streamwise velocity and boundary shear distributions, are presented for a smooth conduit having a cross section similar to that formed between circular rods stacked in a square pattern. This conduit shape was chosen because it displays a large shape effect. Head loss measurements confirmed the significant difference between the friction factor in this conduit shape and that in a pipe. The velocity distributions along normals to the wall followed the universal distribution reasonably well. The velocity and boundary shear distributions are compared with those calculated for this conduit shape using a finite element algorithm described in a previous paper, neglecting secondary flow effects. This comparison illustrates the secondary flow effects, and the difference between the measured and calculated velocity distributions is used to estimate the magnitude of the secondary flow in this conduit shape.