Numerical Analysis of Free Flow over Rectangular Sharp-Crested Compound Weirs

Compound weirs are used as flow diversion structures by adding additional flow resistance to the anticipated regions at the rivers. Furthermore, they are used for measuring and regulating flow rates accurately over a wide range of flow depths. When they are used for this purpose, the cross sections are generally selected as symmetrical having...

Assessment of interfacial turbulence treatment models for free surface flows

The modelling of complex free surface flows is challenging due to the mobility and deformability of the interface and air entrainment characteristics, which are highly affected by turbulence. With the framework of Reynolds averaged Navier–Stokes (RANS) models and the volume of fluid (VOF) method, turbulence quantities at the air–water...

Effects of roughness on hydrodynamic characteristics of a submerged floating tunnel subject to steady currents

The effects of surface roughness as induced by marine fouling on the hydrodynamic forces on a submerged floating tunnel (SFT) are experimentally and numerically investigated in detail at Reynolds numbers Re = 8.125 × 10³–5.25 × 10⁴. A sensitivity analysis to different roughness parameters including roughness height,...

Optimising flow and mixing in a full-scale gas-mixed anaerobic digester by integrating sludge rheological data using computational fluid dynamics

Gas-mixing is commonly applied in anaerobic digesters, yet the resulting flow and hydraulic mixing are difficult to evaluate because of limited full-scale experimental data and uncertainties in integrating sludge rheological data. This study used computational fluid dynamics (CFD) to assess the impact of treated sludge rheology on flow and...

Response of a submerged floating tunnel subject to flow-induced vibration

In order to assess the dynamic performance of a submerged floating tunnel (SFT) subject to flow-induced vibration (FIV) conditions in a practical engineering application, a one-way fluid–structure interaction (FSI) model consisting of multi-scale hydrodynamic solvers combined with the finite element method (FEM) is established. A typical long...

Numerical modelling of flow over sharp-crested rectangular contracted weir

Weirs are flow control structures that can be used for flow diversion purposes. They are classified according to section geometry or their length in the flow direction. For sharp-crested rectangular weirs, Rehbock [1] derived stage-discharge equations. In contracted geometries, streamlines curve at the approach flow leading to variations in flow...

The impacts of internal solitary waves on a submerged floating tunnel

The interaction between an oceanic internal solitary wave (ISW) and a prototype submerged floating tunnel (SFT) is numerically investigated. Effect of oceanic internal solitary wave amplitude, the relative distance of the SFT to the pycnocline, cross-sectional geometry of the SFT, and the density ratio of the two fluid layers are analyzed. At...

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

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...

Optimization of submerged floating tunnel cross section based on parametric Bézier curves and hybrid backpropagation - genetic algorithm

The cross-section geometry of a submerged floating tunnel (SFT) has a large effect on hydrodynamic characteristics, structural behavior and service level, making the tunnel cross section the primary factor in optimizing efficiency. Minimizing the mean drag and the dynamic variability in the lift of the SFT cross section under bi-directional ...

A parametric method for submerged floating tunnel cross-section design

A submerged floating tunnel’s (SFT) cross-sectional geometry is one of the main factors influencing its hydrodynamic characteristics. Minimizing the drag and lift is important for reducing the displacement of the structure and load on the mooring system. In this study, a parametric cross-section design method based on the Bézier curve is used...

Impacts of extreme events on hydrodynamic characteristics of a submerged floating tunnel

A submerged floating tunnel (SFT) is a promising alternative to conventional bridges and tunnels, and can be potentially built in the Qiongzhou Strait in China. However, this area is under the threat of disasters including mega tsunamis and severe storm surges. To evaluate the hydrodynamic loads of the SFT in this hazardous zone subject to...

Characterising the two-phase flow and mixing performance in a gas-mixed anaerobic digester: Importance for scaled-up applications

This study aimed to characterise the gas-liquid flow and mixing behaviour in a gas-mixed anaerobic digester by improving phase interaction modelling using Computational Fluid Dynamics (CFD). A 2D axisymmetric model validated with experimental data was set up using an Eulerian-Eulerian method. Uncertainty factors, including bubble size, phase...