High-concentration ice slurry is a promising and environmentally friendly solution for energy-efficient pipeline cleaning due to its high latent heat and effective scouring ability. A novel mixture model based on the kinetic theory of granular flow incorporating a phase-change melting model and a dynamic wall temperature function has been developed to simulate the dynamic flow and melting behavior of thick ice slurry in a horizontal pipe. Numerical simulations are compared to experimental data, and results primarily focus on the ice slurry flowing distance before complete melting, effective flowing distance, melting characteristics, formation and evolution of the slurry-water interface, as well as the temperature distribution across different regions of the pipe. Results confirm that injection length, concentration, and velocity of the slurry have a significant effect on its flowing distance, and that the ice slurry melting rate gradually decreases. In addition, the ice slurry exhibits a distinct edge-to-center melting pattern, with the outer layers melting first and surrounding the central region. The ice volume fraction decreases from the center toward both ends from the axial direction, and the ice volume fraction is lowest at the bottom and gradually increases with height. The front and rear interfaces between the ice slurry and water appear finger-shaped, however behaving differently due to the viscosity difference. Numerical results are shown to match well the experimental data, providing a useful numerical tool and guidance for the design and operation of ice slurry-based pipeline cleaning systems.

This study investigates tip leakage vortex (TLV) characteristics in helico-axial multiphase pumps at 20% inlet gas void fraction across three flow rates (Q/Qdes = 0.9, 1.0, 1.1). Numerical simulations using the SST k-omega and Eulerian-Eulerian models, validated by high-speed photography, reveal critical coupling among operating conditions, vortex dynamics, and gas-liquid phase distribution. With increasing flow rate from 0.9 to 1.1 Qdes, TLV penetration depth increases by 35% (measured by radial displacement), while peak vorticity intensifies from 22,500 s-1 to 24,500 s-1 at the leading edge. The vortex core migrates toward the impeller hub, with the radial position shifting from r* = 0.990 to r* = 0.983 at mid-chord, developing pronounced three-dimensional characteristics at Q/Qdes = 1.1. Vorticity concentrates at the leading edge (lambda = 0.15-0.25) with peak values exceeding 24,000 s-1, then decays exponentially to below 5,000 s-1 by mid-chord (lambda = 0.5), while turbulent kinetic energy peaks at 1.5-1.6 m & sup2;/s & sup2; in the mid-chord region (lambda = 0.4-0.6). Gas holdup distribution exhibits strong spatial correlation with low-pressure regions, with maximum gas holdup increasing from 0.25 to over 0.4 as flow rate increases, gas volume fractions reaching 0.6-0.75 near the leading edge, and normalized gas phase deviation exceeding 300% at high flow rates, forming a coupled phenomenon where pressure depression promotes gas concentration and subsequently influences vortex structural evolution. These findings reveal TLV-induced gas accumulation is 15-20% higher than previous single-phase studies predicted, with critical implications for multiphase pump efficiency optimization.

The thermal-fluid-structural behavior of a translating aluminum plate in an air-cushion furnace equipped with dual-slot nozzles integrated with multiple jets is numerically investigated, focusing on the effect of the jet-row number. Three configurations are considered: dual-slot without multiple jets (DS-NoMJ), with a single-row of multiple jets (DS-SRMJ), and with double rows of multiple jets (DS-DRMJ). The results show that increasing the jet-row number enhances convective heat transfer but significantly modifies the pressure distribution and deformation characteristics. The average Nusselt number increases by about 18% and 27% for DS-SRMJ and DS-DRMJ, respectively, compared with DS-NoMJ. However, temperature uniformity decreases as the number of jet rows increases, with the temperature uniformity index decreasing from 0.757 (DS-NoMJ) to 0.703 (DS-DRMJ). With DS-NoMJ and DS-SRMJ, the plate exhibits a stable wave-like deformation pattern with small amplitudes (7.39 mm and 8.59 mm), associated with symmetric recirculation and gradual pressure redistribution. In contrast, DS-DRMJ produces disordered vortical structures and localized stagnation pressure concentration, leading to high pressure difference between the upper and lower air cushions and severe central bulging of the plate, with maximum deformation reaching 23.74 mm. The single-row multiple-jet configuration provides the best compromise between heat transfer enhancement and aerodynamic stability, achieving intensified heat transfer while maintaining acceptable temperature uniformity and small deformation. These results clarify the role of the number of jet rows in coupling flow organization, pressure loading, and structural response.

Solar energy is one of the fastest-growing contributors to the global energy market. Floating photovoltaic (FPV) systems have emerged as a promising solution to the land-use challenges faced by conventional solar farms. However, the extension of FPV systems to offshore environments is hindered by dynamic wave-structure interactions. Inspired by air-cushion vessels, this study proposes and experimentally validates a novel FPV platform supported by an inflatable air cushion that provides adjustable stiffness and passive damping through air compressibility and wave-induced volumetric deformation. The investigated platform adopts a symmetric structural configuration, which inherently mitigates asymmetric roll and yaw coupling to maintain a balanced hydrodynamic response and stable power generation under wave action. Wave tank experiments were conducted to evaluate the coupled hydro-elastic response, mooring loads, and power generation stability under varying wave heights. The results show that the air-cushion design can significantly reduce peak mooring loads by over 50% compared with the catamaran benchmark. The highest pressure of 20 mbar increases structural stiffness but causes wave-induced losses of up to 30%. Conversely, the lowest pressure of 5 mbar results in excessive compliance that amplifies pitch and heave motion. A moderate pressure of 10 mbar acts as the optimal damping condition within the tested pressure range, suppressing motion resonance while maintaining power output stability. These findings demonstrate the potential of air-cushion integration for offshore FPV adaptability.

High-concentration ice slurry with phase change can be used as a pipe cleaning material, producing pollution-free effluents. The required characteristics of such slurry should be determined carefully before any cleaning process to slow down its melting rate and reduce cleaning costs. Excessive pump power should be avoided to minimize energy consumption, as well as high pressure on the pipeline wall to prevent pipe breakage. In this study, the flow and melting of high-concentration ice slurry were experimentally investigated in a closed-loop pipe system to examine the impact of key parameters on ice pigging. Results show that ice slurry exhibits effective cleaning performance during steady flow. The melting at the front of the slurry appears more pronounced due to the significant temperature difference between its front and the pipe wall, as well as the large heat exchange at the interface between the slurry front and the surrounding water. The melting rate of the ice slurry increases with flow acceleration, and the flowing distance increases with the slurry injection length, concentration, and flow velocity. The wall shear stress exerted by the ice slurry also increases with these parameters, and its rate of change is closely related to the velocity gradient near the boundary layer. A novel predictive formulation was developed to estimate the ice slurry flowing distance, featuring high accuracy and low experimental data requirements, by combining a physical modelling approach with a Gradient Boosting Regressor process. This research provides important information for the practical application of ice slurry in cleaning operations.

Floating photovoltaic (FPV) systems offer a promising route for expanding solar generation in coastal and offshore water bodies. However, wave-induced motion, mooring loads, and intermodule forces govern their viability. Excessive motion reduces energy yield, amplifies connector and mooring tensions, and threatens long-term reliability, making accurate hydrodynamic prediction essential for design. Most current CFD studies focus on single-row floaters, typically barge or catamaran-type platforms connected by rigid or hinged connections, leaving the behaviour of multi-row FPVs with compliant inter-module connections largely unexplored. This study develops and validates a high-fidelity CFD framework for rope-mesh FPV arrays, implementing a novel in-memory spring-connector formulation within OpenFOAM's rigidBodyMotion framework to represent compliant, tensioned rope connections. The approach is validated against wave tank experiments for both single-module and 2 & times;2 array configurations. Validation demonstrates excellent accuracy, with heave and pitch RAO errors within 5-13% across wavelengths. The framework successfully captures multi-body interaction effects, including wave-field shielding that reduces aft-row response by upto 10%. Direct comparison demonstrates that conventional rigid joints underpredict pitch by over 20% and overestimate heave by 18%, while the spring connector maintains errors within 5-13%, confirming the necessity of force-based compliant coupling for accurate rope-mesh FPV prediction. Connector force analysis reveals that streamwise connectors experience forces 3-5 times larger than transverse connectors, with peak forces occurring at lambda/L approximate to 2.5-3.5, where phase differences maximise differential motion between rows. These results establish streamwise connections as the critical design drivers for rope-mesh FPV systems under head-sea loading.

The deformation behavior of an aluminum plate during heat treatment in an air-cushion furnace is numerically investigated, focusing on the effect of nozzle inclination angle. Validation of the numerical results was implemented with experimental data obtained from a specifically built experimental rig. The results reveal that at nozzle inclination angles of 30 degrees, 45 degrees, and 75 degrees, the plate exhibits significant downward deflection in the central region, with the maximum deformation (60.3 mm) occurring at 45 degrees. In contrast, a distinct wave-like deformation pattern with the minimal deformation (7.39 mm) arises at 60 degrees, attributed to cross-flow interaction and the shear effect induced by plate motion. Consistency of the wave-like pattern is demonstrated at adjacent angles (57 degrees and 62 degrees). At an inclination angle of 60 degrees, symmetric recirculating flows are reinforced, and the most uniform temperature distribution (average surface temperature of 463 K and temperature uniformity index of 0.757) is achieved. These findings highlight the critical role of nozzle inclination angle in reducing deformation and improving heat treatment quality, offering practical insights for industrial applications.

Heat treatment of an aluminum sheet through a gas-cushion furnace is numerically investigated. The sheet of 0.6 mm thick was suspended due to simultaneous impingement of upward and downward gas jets. Effects of Reynolds number (Re = 8,000-32,000) and upper/lower distance ratio (du/dl = 3:5, 1:1, 5:3) on flow and heat transfer characteristics were investigated, along with the structural characteristics of the sheet. The validation of the numerical results was implemented though experimental data. The results indicate that an increase in Re leads to an increase in circulating flow intensity in the gas-cushion furnace, due to an increase in the peak value of Nusselt number (Nu). However, the variation of Re imposes an insignificant effect on the pressure coefficient distribution over the sheet. At Re = 24,000, an upward deformation is evidenced at the middle part of the sheet. As Re decreases to 16,000, relatively slight downward deformation appears at the middle part of the sheet. At an upper/lower distance ratio of 3:5, a uniform pressure distribution is obtained at the lower surface of the sheet. Furthermore, the near-wall flow in the middle part of the sheet brings benefits, and such a layout is responsible for high average temperature of the sheet.

Land availability constraints limit the installation of conventional ground-mounted solar installations. As a result, Floating Photovoltaic (FPV) systems are gaining popularity as an alternative to renewable energy generation. FPV consist of individual solar panels that are commonly symmetrical and modular. However, the hydrodynamic behaviour of FPVs in water surface waves is understudied to ensure their stability and optimal performance under varying environmental conditions. This literature review examines various modelling techniques applied in studying FPV hydrodynamics. Specifically, the application of Computational Fluid Dynamics (CFD) solvers and potential flow theory solvers is investigated for their effectiveness in capturing the behaviour of FPVs and mooring dynamics under the impact of wind and waves. The review highlights the advantages and limitations of each approach. Findings suggest that a combined CFD-potential flow approach offers a perfect balance between accuracy and computational efficiency, offering valuable insights into the performance of FPVs. However, extensive research is notably absent in hydrodynamic modelling for large-scale FPVs. This lack of research represents a significant gap in our current study on multiscale FPV systems.

The growing demand for sustainable energy solutions and the limitations of land-based solar installations have spurred interest in floating photovoltaic (FPV) systems. This study presents an experimental investigation of the hydrodynamic performance of modular FPV systems using an innovative Rope Mesh model. The research assesses key parameters such as the Response Amplitude Operator (RAO) and mooring forces under different wave conditions. Experiments conducted at Cranfield University evaluated the hydrodynamic responses and mooring performance of scaled-down models in controlled wave environments. The study examined the pitch and heave motion of single-body and multi-body FPV systems subjected to different wave heights and wavelengths. Results demonstrate that the modular design of the platforms can effectively withstand a range of marine conditions with minimal impact on solar panel performance in most cases. The findings provide critical insights into optimising FPV systems for nearshore and offshore applications, supporting the development of more resilient and efficient renewable energy solutions.

This research uses 3D Computational Fluid Dynamics (CFD) simulations to investigate the downhole Natural Gas Separation Efficiency (NGSE) for multiphase pumping wells in the heterogeneous churn flow regime. Results explain the effects of key parameters such as liquid viscosity, intake port sizes/diameter, and casing diameter, on the NGSE. Methods are thus suggested to enhance the NGSE in oil field operations, and key improvements to the widely used mathematical formulations for viscous service are proposed. Transient numerical simulations were performed for a section of an experimental flow loop extracted from the literature, and the flow solution was obtained with the Volume of Fluid (VOF) model. For most simulations, turbulence effects were modelled with the $ k - \varepsilon $ k-& varepsilon; turbulence model. The $ k - \omega $ k-omega SST turbulence model was however considered for the sensitivity analysis on liquid viscosity. The final numerical results validated against the corresponding experimental data showed an average error of less than 6%. Combining past literature and current results confirms that (i), the NGSE is affected by the downhole geometry (i.e annulus space and pump intake port flow area geometry) and (ii), current analytical NGSE models are not ideal for multiphase viscous service (high viscosity Newtonian flow) in the heterogeneous flow regime. The widely used steady-state formulations might thus not be adequate for this flow regime.

An improved implicit direct-forcing immersed boundary method (DF-IBM) is presented for simulating incompressible flows around complex rigid structures undergoing arbitrary motion. The current approach harnesses the pressure implicit with splitting of operators algorithm to handle the fluid-solid system's dual constraints in a segregated manner. As a result, the divergence-free condition is preserved throughout the Eulerian domain, and the no-slip velocity boundary condition is exactly enforced on the immersed boundary. A new pressure Poisson equation (PPE) is derived, incorporating the boundary force where the no-slip condition is already met, enabling the use of fast iterative PPE solvers without modifications. The improvement involves integrating Lagrangian weight methods having better reciprocity over the IBM-related linear operators with the implicit formulation. An additional force initialization scheme is introduced to further boost the algorithm's performance. The method's accuracy, efficiency, and capability are verified through various stationary and moving immersed boundary cases. The results are validated against experimental and numerical data from the literature. The proposed improvements seamlessly integrate into existing incompressible fluid solvers with minimal adjustments to the original system equations, highlighting their ease of implementation.

Free-floating and submerged wave energy converters (SWECs) are regarded as promising technologies for renewable energy production. These converters rely on a heave-motion buoy to capture the kinetic energy of ocean waves and convert it into electrical energy through power conversion systems. To better understand the impact of various factors on power generation and efficiency, the effects of different buoy shapes (rectangular, circular cylinder, and trapezoidal fin), submergence depths (0, 0.1, and 0.2 m), wave heights (0.04, 0.06, and 0.1 m), and spring stiffness (50 and 100 N/m) were investigated. A 2D numerical wave tank with a buoy was simulated, and the results were validated against experimental data. Information on vorticity, vertical displacement, power absorption, and efficiency are provided. The findings indicate that the buoy shape and wave height significantly affect power absorption and efficiency. Additionally, this study reveals that increasing submergence leads to higher power absorption and lower conversion efficiency.

Foam flooding by Foam Assisted Water-Alternating-Gas (FAWAG) is an important enhanced oil recovery method that has proven successful in experimental and pilot studies. The present study is carried out to monitor the movement of the foam front once injected into the porous medium. This study aims to investigate applications of resistivity waves to monitor foam propagation in a sandstone formation. In the present lab-scale experiments and simulations, resistivity measurements were carried out to monitor the progression of foam in a sand pack, and the relationships between foam injection time and resistivity, as well as brine saturation, were studied. The brine saturation from foam simulation using CMG STAR is exported to COMSOL and calculated true formation resistivity. A diagram was produced summarizing the progression of foam through the sand pack in the function of time, which enabled us to establish how foam progressed through a porous medium. A surfactant and brine mixture was injected into the sand pack, followed by nitrogen gas to generate the foam in situ. As foam progressed through the sand pack, resistance measurements were taken in three zones of the sand pack. The resistance was then converted into resistivity and finally into brine saturation. As foam travels through the sand pack, it is predicted to displace the brine initially in place. This gradually increases each zone's resistivity (decreases the brine saturation) by displacing the brine. Also, an increase in the surfactant concentration results in higher resistivity. Finally, a comparison of three different surfactant concentrations was evaluated in terms of resistivity results, water saturation, and foam propagation monitoring to obtain the optimum surfactant concentration involved in foam flooding.

In the global pursuit of Net Zero emissions by 2050, wind turbines have become a leading solution.These renewable energy generators offer a trifecta of benefits, significantly reducing CO 2 emissions, minimizing environmental impact, and delivering cost-competitive clean power.However, the key to maximizing their potential lies in the aerodynamic design of the turbine blades.By improving the blade performance, researchers and engineers can significantly increase wind energy capture, propelling wind turbines to the forefront of the global transition to a sustainable future.Higher power generating wind turbines are needed to reach the Net Zero target.By upscaling the "DTU 10 MW Reference Wind Turbine", this research has achieved an aerodynamically stable 20 MW offshore wind turbine blade design.Variable rotation speed and variable pitch angle configurations have been considered to achieve an ideal power curve.The aerodynamic performance has been evaluated and quantified for a length optimised blade design, wherein the power and thrust have been increased by 80.84% and 88.67%, respectively, at a rated wind velocity of 12 m/s.

Ice slurry is a phase-changing material composed of liquid water, ice crystals, and a freezing point depressant. It is finer and more uniform compared to ice cubes or flake ices and is used in many industries, such as food preservation, comfortable cooling, medical protective cooling, sport cooling, instrument cooling, firefighting, and artificial snowmaking, due to its high energy storage density. Ice slurry with high concentration can be used for cleaning equipment as its friction is several times greater than that of water at the same flow rate. This paper describes in detail the developments of ice slurry, including production methods, concentration measurement approaches, flow and heat transfer characteristics, as well as its applications in various industries. Problems to be solved or improved are also discussed, providing suggestions for better developments and applications in industrial environments.

A pressure correction method is proposed considering the influence of a dual factor. The applicability of a pressure correction method coupled with a drag model is discussed along with the accuracy of the simulation results obtained by such a pressure correction method. It is found that the present pressure correction method combined with the DBS (dual bubble size) drag model can accurately reflect the changing trend of gas holdup distribution with pressure. It is also established that results from this model applied to a bubble column match well with the experimental data. Finally, when compared with other pressure correction models, the proposed model shows better robustness in three-dimensional simulations and can predict radial gas holdup distributions with better accuracy. A new pressure correction method considering dual parameters is proposed. Its applicability when coupled with the drag model is examined, along with the accuracy of simulation results. The method, combined with a dual bubble size drag model, accurately reflects gas holdup distribution changes with pressure. When applied to bubble columns, it shows good agreement with experimental data. image

Impinging jet is one of the most efficient techniques to achieve a high heat transfer coefficient and is used in many engineering applications. The present study focuses on the effect of nozzle shape on fluid behavior and heat transfer characteristics. For the current investigation, circular, square, rectangular, and elliptical nozzles with identical hydraulic diameters are used with Reynolds number Re ranging from 15,000–35,000. The circular nozzle results are validated with the published numerical and experimental data. In the current study, it is found that as the Reynolds number increases, the value of the averaged Nusselt number increases in all circumstances. When examining the different nozzle shapes, the value of the averaged Nusselt number is higher when an elliptical nozzle is used. The contours of the surface Nusselt number and velocity streamlines are also presented. The contour shows that the heat flux is highest in the stagnation zone and gradually decreases to the sides because they are outside the impingent coverage. Moreover, the area between the jets has a low heat flux. The heat transfer in the impinging zone is initially raised as the jet-induced crossflow increases and achieves a peak value, and then reduced stream-wise because of the crossflow effect.

Computational fluid dynamics (CFD) techniques can predict complex fluid flow structures and the thermal performance of jet impingement systems. Numerical studies can complement extensive and time-consuming experimental studies where local parameter measurements are difficult and costly to obtain. In the current work, a combination of one, four, and nine square jets impingements are numerically investigated with CFD for mass flow rate (m) ranging from 2.71 × 10-4 to 7.40 × 10-4 kg/s. The effects of the jet's outlet-to-target plate distance (Z) are assessed as a function of the width of a single square nozzle (B). The flow field features of different nozzle configurations are also studied. It is shown that the Nusselt number increases as the mass flow rate increases, but increases inversely as the dimensionless jet's outlet-to-target plate spacing Z/B increases. The numerical investigation also demonstrates that when increasing the number of nozzles under a constant mass flow rate, the Nusselt number significantly increases. The effect of nozzle configuration is not that significant at Z/B > 7. It is found that the present impinging jet system offers about 63% enhancement in thermal efficiency, while the pumping power increases by 3.7 times. All simulations are successfully validated with experimental data.

Small vertical axis wind turbines (VAWTs) are often considered suitable for use in urban areas due to their compact design. However, they are also well known to offer poor performance at low wind speeds, which is a common situation in such environments. An optimised 3D J-shaped VAWT was designed from standard NACA 0015 blades and analysed numerically through computational fluid dynamics (CFD). A finite element analysis (FEA) was also carried out to ensure the model’s structural integrity. Optimal results were obtained with aluminium alloy hollow blades and stainless-steel struts with X-shaped beams, with internal ribs. Numerical results showed that the J-shaped VAWT achieved an 18.34% higher moment coefficient compared to a NACA 0015-based VAWT, indicating better self-starting abilities.