Wave-tubular member—wave and current interaction

The in-line hydrodynamic forces on submerged tubular members have been investigated experimentally for different positional depths (.z/h), relative clearances (e/D), diameter-to-water depth ratios (D/h), and horizontal gap-to-diameter ratios (G/D). The forces due to wave-current interaction on the tubular members near the free surface show an increase of about 40% for D/h = 0.20, compared with the force due to wave action only. For the tubular members located near the bed, the increase is on the order of 80%, irrespective of D/h. The results indicate that tubular members behave as an independent unit for G/D > 2.7, and the varation of dimensionless force FDm with z/h, instead of in terms of e/D, is a unique approach. Variation of drag and inertia coefficients indicate that these coefficients are functions of z/h, D/h, and G/D, in addition to Reynolds number. Scale effects on the prototype prediction of force are also critically discussed. © ASCE.