Submerged floating tunnel cross-section analysis using a transition turbulence model

Abstract

Concepts of a submerged floating tunnel (SFT) for novel sea-crossings have been researched in recent years. An SFT tube should be moored afloat by tensioned mooring systems to maintain the tube position under complex hydrodynamic loads. In-line force is amongst the dominant hydrodynamic parameters in the SFT cross-section design and the mooring system reliability evaluation. Selecting a suitable in-line force computation method is crucial to successful and accurate SFT cross-section optimization. The transition SST model is an effective turbulence transition prediction tool in the boundary layer computation subjected to tidal flow at both low and high Reynolds numbers. Two types of parametric Bézier curves applied in airfoil optimization are used to describe the SFT cross-section. We show that an SFT cross-section described by a leading-edge Bézier-PARSEC (BP) curve has better hydrodynamic performance than a trailing-edge BP curve of equal aspect ratio (AR). To avoid large flow separation, an AR not exceeding 0.47 is recommended. An SFT cross-section design should balance hydrodynamic performance and construction cost. The SFT cross-section with AR = 0.47 using the leading-edge BP curve with fixed clearance has a comparatively small in-line force and a minimum material cost.

Numerical Investigations of Hydrodynamic Characteristics of a Marinefouled Submerged Floating Tunnel

“…The influence of SFT cross-section shape, roughness height, and fouling coverage ratio on the hydrodynamic forces of an SFT are comparatively analyzed under various current conditions. Unsteady Reynolds Averaged Navier-Stokes (URANS) based transitional turbulence models are applied for flow characteristics predictions such as flow separation, vortex shedding, and wake parameters ( Zou et al, 2021). The transient solver PimpleFoam, supplied with OpenFOAM, for incompressible, turbulent flow is applied for current conditions.…”