Mean and unsteady loading on square prisms with rounded edges: Hard marine growth, incidence, and Reynolds number effects

Abstract A set of wind tunnel experiments was performed to study the average and fluctuating loading on an ”infinite” 2D square prism with rounded edges r / D = 0.16 for different heights simulated hard marine growth at sub-to transcritical Reynolds numbers. It has already been shown, that a change in surface roughness from ks/D = 4.5 × 10?6 (smooth) 1 10?3 (rough) similar ? = 0° 45° had large effects widths numbers marking boundaries various flow states. At ? = 45° it furthermore led Reynolds-number independency lift drag forces Strouhal number. For present tests two additional values ks/D were selected obtain smaller increments roughness: 4.5 10-4 (slightly rough) 1.4 (very rough). Mean forces, main vortex shedding frequency, distributions mean pressures mid-span cross-section wake profiles recorded simultaneously. The same static angles incidence, 45°, investigated R e  = 60,000–12 million. prisms smooth up rough surfaces strong behaviour all aerodynamic parameters number found, whereas further increase induced hardly any effects. absolute found be independent supercritical slightly state  = 12 million, rougher upper transition states appeared high little variation coefficients. overall force coefficients caused by motions transition, separation reattachment locations.