Slurry pipe transport has directed the efforts of researchers for decades, not only for the practical impact of this problem, but also for the challenges in understanding and modelling the complex phenomena involved. The increase in computer power and the diffusion of multipurpose codes based on Computational Fluid Dynamics (CFD) have opened up the opportunity to gather information on slurry pipe flows at the local level, in contrast with the traditional approaches of simplified theoretical modelling which are mainly based on a macroscopic description of the flow. This review paper discusses the potential of CFD for simulating slurry pipe flows. A comprehensive description of the modelling methods will be presented, followed by an overview of significant publications on the topic. However, the main focus will be the assessment of the potential and the challenges of the CFD approach, underlying the essential interplay between CFD simulations and experiments, discussing the main sources of uncertainty of CFD models, and evaluating existing models based on their interpretative or predictive capacity. This work aims at providing a solid ground for students, academics, and professional engineers dealing with slurry pipe transport, but it will also provide a methodological approach that goes beyond the specific application.

The shear behavior and dynamic response of a steel–silt interface are significant for the safety and stability of offshore structures in the Yellow River Delta. A series of steel–silt interface cyclic shear tests under constant normal load conditions (CNL) were carried out to explore the effects of normal stress, shear amplitude, roughness, and water content on the interface shear strength, shear stiffness, and damping ratio using a large interface shear apparatus. The preliminary results showed that the amplitude of normal stress and shear amplitude affected the interface’s shear strength, stiffness, and damping ratio in a dominant manner. The roughness and water content were also crucial factors impacting the rule of shear strength, shear stiffness, and damping ratio, changing with the number of cycles. Under various scenarios, the steel–silt interface weakened distinctively, and the energy dissipation tended to be asymptotic with the cyclic shear.

Pipe bend is a critical integral component, widely used in slurry pipeline systems involving various engineering applications, including natural gas hydrate production. The aim of this study is to assess the capability of RANS-based CFD models to capture the main features of the turbulent single-phase flow in pipe bends, in view of the future investigation of the hydrate slurry flow in the same geometry. This is different from the available literature in which only a few accounted for the effects of a combination of computational mesh, turbulence model, and near-wall treatment approach. In this study, three types of mesh configuration were adopted to carry out the computations, namely unstructured mesh and two structured meshes with a uniform and nonuniform inflation layer, respectively. To explore the influence of the turbulence model, standard k-ε, low-Reynolds k-ε, and nonlinear eddy viscosity turbulence model were selected to close RANS equations. Pressure coefficient, mean axial velocity, turbulence intensity, secondary flow velocity, and magnitude of secondary flow were regarded as the critical variables to make a comprehensive sensitivity analysis. Predicted results suggest that turbulent kinetic energy is the most sensitive variable to the computational mesh while others tend to stabilize. The largest difference of turbulence kinetic energy was around 26% between unstructured mesh and structured mesh with a nonuniform inflation layer. Additionally, a fully resolved boundary layer can reduce the sensitivity of mesh on turbulent kinetic energy, especially for a nonlinear turbulence model. However, the large gradient and peak value of turbulence intensity near the inner wall of the bend was not captured by the case with a fully resolved boundary layer, compared with that of the wall function used. Furthermore, it has been confirmed that the same rule was detected also for different curvature ratios, Reynolds numbers, and dimensionless wall distance y+.

The interaction between soil and structure is a research hotspot in ocean engineering, and the shear performance of interfaces is an essential factor affecting the bearing capacity of offshore structures. Taking the Yellow River Underwater Delta as the research area, the Softening/Hardening damage model of the silt–steel interface and the determination method of model parameters are proposed based on the statistical damage theory. Through the interface monotonic shear test under the conditions of different normal stress, roughness and water content, the shear mechanical properties and volumetric deformation laws on the silt–steel interface are analyzed, and the damage model parameters are obtained. Finally, a FRIC subroutine for the damage model was developed based on ABAQUS. The research results indicate the following: (1) The interface between silt and steel exhibits two characteristics, softening/hardening and shear shrinkage/expansion, under different conditions. Roughness significantly impacts interfacial cohesion, while water content mainly affects the internal friction angle. (2) The softening model based on the classic rock damage model can better simulate the stress–strain relationship of the silt–steel interface under high normal stress and low water content. In contrast, the hardening model based on the classic hyperbola model can better simulate the stress–strain relationship under low normal stress and high water content. The calculated results of the softening/hardening model agree with the experimental results, and the model has 7 parameters. (3) The developed FRIC subroutine can effectively simulate the nonlinear mechanical behavior of the interface between silt and steel. The research results provide a reference for exploring the stability analysis of offshore structures considering interface weakening effects.

The understanding and prediction of slurry flow behavior in pipeline systems is critical for successful operation and management of various industrial applications due to the inherent complexity of such solid–liquid mixtures. Thus, fundamental experimental investigations and an easy-to-use, efficient computational fluid dynamics model meeting engineering requirements are essential. This study first preliminarily explores the physical process of slurry flow, composed of uniformly graded glass beads at different concentrations, via laboratory tests. These tests use electrical impedance tomography (EIT) and sampling probe techniques to measure particle volume fraction distribution in a 100 mm diameter pipe. A key contribution is a novel, efficient two-fluid model requiring calibration of one parameter, turbulent Schmidt number σ: it offers fast predictions and reasonable estimates of concentration profiles and hydraulic gradients in horizontal pipes post-calibration, assuming full particle suspension (in situ concentration ideally <30% v/v) and neglecting particle–particle interactions. The study finds σ primarily depends on pipe diameter and establishes potential correlations between σ, pipe diameter, and Reynolds number, simplifying calibration across flow conditions and geometries. While not a fundamental theoretical advance, the proposed model enhances predictive capability by minimizing empirical uncertainty and enabling reliable extrapolation beyond validation cases. Moreover, experimental results confirm that EIT provides a qualitative yet robust visualization of particle distribution, demonstrating its promise when integrated with advanced reconstruction algorithms. These findings provide both theoretical insight and practical tools for slurry transport analysis, with particular value in engineering contexts, such as dredging, mining, and offshore pipeline operations.

In this study, we present, test, and make available to the scientific community the betaSigmaSlurryFoam solver, which is a two-phase model based on the Eulerian-Eulerian approach for the simulation of turbulent slurry transport in piping systems. Specifically, betaSigmaSlurryFoam is a fully open source implementation, within the OpenFOAM platform, of the existing $\beta$-$\sigma$ two-fluid model, developed over a decade by researchers at Politecnico di Milano, which, as certified by scientific publications, proved an effective way to simulate the pipe flow of fine particle slurries in the pseudo-homogeneous regime. In this paper, we first provide the mathematical and coding details of betaSigmaSlurryFoam. Afterwards, we verify the new solver by comparison with the earlier $\beta$-$\sigma$ two-fluid model for the case of slurry transport in a horizontal pipe, demonstrating not only that the two solutions are very close to each other, but also that the effects of the two calibration coefficients $\beta$ and $\sigma$ are the same for the two implementations. Finally, we apply betaSigmaSlurryFoam to the more complex case of slurry transport in a horizontal pipe elbow, which has never been subject to investigation using the earlier $\beta$-$\sigma$ two-fluid model. We prove that the solution of betaSigmaSlurryFoam is physically consistent, and, after assessing the impact of $\beta$ and $\sigma$ through an extensive sensitivity analysis, we show that reasonably good agreement could be achieved against experimental data reported in the literature even for slightly different particle sizes than those considered in our previous research. The sharing of betaSigmaSlurryFoam as open source code promotes its further development by fostering collaboration between research groups worldwide.