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 $D/h=0.20\text{,}$ 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 $G/D>2.7\text{,}$ and the varation of dimensionless force $F_{\mathrm{DIM}}$ 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.