Unsteady numerical investigation of shallow water effects on the resistance of inland waterway vessels

Paper in proceeding, 2026

Inland waterway transport is increasingly regarded as a low-carbon alternative to road transport. However, vessels operating in confined, shallow waterways experience hydrodynamic effects that differ fundamentally from those in deep water. As the depth-to-draught ratio H/T decreases, flow confinement beneath the hull induces additional resistance and alters the pressure distribution, leading to increased sinkage and bow-down trim, with direct implications for energy efficiency and navigational safety. This study presents unsteady Reynolds-averaged Navier–Stokes (URANS) simulations of a model-scale (1:16) CEMT Class-Vb inland cargo vessel to investigate its hydrodynamic behaviour in shallow water. The free surface is resolved using a volume-of-fluid (VoF) method, turbulence is modelled with the SST k–ω model, and vessel motions are captured via a DFBI morphing approach, enabling the vessel to reach equilibrium sinkage and trim while capturing persistent low-amplitude oscillations in resistance and motions. The simulations are validated against previously published towing tank measurements for H/T=2.0 and 1.5 and extended to an extremely shallow-water case of H/T=1.2. The results reveal pronounced shallow-water effects on ship resistance and motion, highlighting the need for an accurate numerical tool for ship hydrodynamic prediction that enables energy-efficient, safe navigation of inland waterway vessels.