Search Results (160)

Nowadays various coupling strategies have been developed to combine the strengths of different numerical methods in computational fluid dynamics (CFD), among which the coupled algorithm of the lattice Boltzmann-finite volume method (LBM-FVM) has gained widespread attention. However, research on parallel optimization of LBM-FVM coupled solvers remains limited, mostly focused on independent solvers. In this work, we proposed a flexible framework and optimization schemes to explore the coordinated balance of accuracy-efficiency-hardware adaptability. First, we designed a processor layout strategy to address load imbalance and communication redundancy in the coupled solver. We then developed several parallelization techniques, including LBM restructuring, data reuse, and SIMD optimization for targeted kernels on the most advanced architecture of the Sunway series in China, namely SW26010P heterogeneous many-core processors, which provide hardware architectural advantages well suited for large-scale parallel computational fluid dynamics. Finally, the accuracy of the LBM-FVM coupling simulations was validated through benchmark simulations of 2D/3D lid-driven cavity flow. The results show that our LBM-FVM coupling solver can accurately capture flow characteristics, with vortex structures consistent with experimental data. Additionally, we achieved a 152× speedup for the LBM solver and a 126× speedup for the coupled simulation compared to the standalone FVM simulation on the New Sunway supercomputer system. Our approach marks a milestone in the field of LBM implementations and provides a promising future for coupled algorithms in CFD. Full article

Direct Numerical Simulations (DNS) are widely employed to simulate thermo-fluid dynamics in packed bed reactors, offering high-fidelity insights into complex flow and heat transfer phenomena. However, recent studies have revealed notable differences in isothermal turbulent flow results across different DNS frameworks, leaving open the question of how conjugate heat transfer is affected. This study presents a comparison between DNS based on a finite volume method (FVM) and a lattice Boltzmann method (LBM) for predicting turbulent heat transfer in a low porosity face-centered cubic (FCC) packed unit. First, the methods are compared with respect to the required resolution and computational cost. Subsequently, global parameters for drag, heat transfer, and spatial as well as temporal variances are evaluated. The flow topology is further analyzed by examining the mean and fluctuating components of hydrodynamic and thermal fields. While good agreement between the methods is shown regarding time-averaged velocity and temperature profiles, more pronounced differences are observed when comparing the respective temporal variances between the two methods. Additionally, the FVM, which relies on a surface-fitted mesh, requires more degrees of freedom to obtain a grid-converged solution but delivers results of higher certainty than the LBM. These findings highlight important methodological considerations when selecting DNS approaches for resolving turbulent heat transfer in complex porous geometries. Full article

We present a new finite element framework for modeling compressible, turbulent multiphase flows with heat transfer. For two-fluid systems with a free surface, the Volume of Fluid (VOF) method is implemented without the need for interface reconstruction, while turbulence is resolved using a dynamic Vreman large eddy simulation (LES) model. Unlike most two-phase VOF studies, which neglect heat transfer, the present approach incorporates energy transport equations within the VOF formulation to account for heat exchange, an effect particularly important in turbulent flows. Conjugate heat transfer is often challenging in finite volume methods, which require explicit specification of heat fluxes at the solid–fluid interface, limiting accuracy and predictive capability. By contrast, the finite element formulation does not require heat flux inputs, allowing more accurate and robust simulation of heat transfer between solids and fluids. The method is demonstrated through three representative cases. First, a two-fluid instability with a single-mode perturbation is simulated and validated against analytical growth rates. Second, conjugate heat transfer is examined in a high-temperature flow over a cold metal cylinder, with validation performed both quantitatively—via pressure coefficient comparisons with experimental data—and qualitatively using vector field topology. Finally, compressible spray injection and breakup are modeled, demonstrating the ability of the framework to capture interfacial dynamics and atomization under turbulent, high-speed conditions. In the compressible spray injection and breakup case, the results indicate that the finite element formulation achieved higher predictive accuracy and robustness than the finite-volume method. With the same mesh resolution, the FEM reduced the root mean square error (RMSE) and mean absolute percentage error (MAPE) from 6.96 mm and 26.0% (for the FVM) to 4.85 mm and 12.7%, respectively, demonstrating improved accuracy and robustness in capturing interfacial dynamics and heat transfer. The study also introduced vector field topology to visualize and interpret coherent flow structures and instabilities, offering insights beyond conventional scalar-field analyses. Full article

The fast and accurate calculation of the internal temperature rise in the oil-immersed transformer is the premise to realize the thermal health management and load energy evaluation of the in-service transformer. In view of the influence of nanofluids on the heat transfer process of transformer, a numerical simulation algorithm based on lattice Boltzmann method (LBM) and finite difference method (FDM) is proposed to study the heat and mass transfer process inside nano-modified oil-immersed transformer. Firstly, the D2Q9 lattice model is used to solve the fluid and thermal lattice Boltzmann equations inside the oil-immersed transformer at the mesoscopic scale, and the temperature field and velocity field are obtained by macroscopic transformation. Secondly, the electric field distribution inside the oil-immersed transformer is calculated by FDM. The viscous resistance in LBM analysis and the electric field force in FDM analysis, as well as the gravity and buoyancy of particles, are used to explore the motion characteristics of nanoparticles and metal particles. Finally, compared with the thermal ring method and the finite volume method (FVM), the relative error is less than 5%, which verifies the effectiveness of the numerical model and provides a method for studying the internal electrothermal convection of nano-modified oil-immersed transformers. Full article

Nanofluids are an important technology for enhancing heat transfer in industrial applications by incorporating high thermal conductivity nanoparticles into base fluids. However, they often require higher pumping power and energy consumption. This study employs a two-dimensional (2D) approximation of vortex generators (VGs) in a turbulent trapezoidal channel with nanoparticle concentrations of ${\mathrm{Al}}_2{\mathrm{O}}_3$, ${\mathrm{SiO}}_2$, and ${\mathrm{TiO}}_2$. Simulations are performed using ANSYS Fluent 2021 with the Finite Volume Method (FVM) and the k–$\epsilon$ turbulence model to capture turbulence characteristics, eddy viscosity, and turbulent kinetic energy production. The introduction of vortex generators improves fluid mixing and reduces the thermal boundary layer, resulting in enhanced heat transfer, with a performance evaluation criterion (PEC) of 1.08 for water (baseline case without nanofluids). The single nanofluids further optimize heat transfer, increasing the Nusselt number and pressure drop while balancing thermal performance, reaching a PEC of 1.6 for ${\mathrm{SiO}}_2$ at 3% concentration, representing a 48% improvement over the baseline. A hybrid mixture of 1% ${\mathrm{Al}}_2{\mathrm{O}}_3$ and 2% ${\mathrm{SiO}}_2$ achieves the same PEC of 1.6 as single ${\mathrm{SiO}}_2$ nanoparticles, but with higher heat transfer and lower pressure drop, demonstrating improved thermal performance. Full article

To gain deeper insights into the influence of pipe parameters on water hammer properties and achieve the accurate simulation of the hydraulic transient process in pipeline systems, the Finite Volume Method (FVM) is adopted. The solution scheme, incorporating a second-order MUSCL-type reconstruction, is derived, and the numerical solution process is detailed. For enhanced accuracy, the unsteady friction term is included in the numerical solution of the governing water hammer equations. The method is validated through a comparison with experimental data and the verification of mesh and Courant number independence, confirming both its efficiency and accuracy. The calculation error of the peak water head is less than 5%. Finally, an engineering case is studied to investigate valve arrangement and operation. Optimization yields the optimal valve position and operating parameters. This analysis provides valuable reference for pipeline system design. Full article

The manufacturing of multiscale composite structures in aerospace engineering is governed by complex interactions among material heterogeneity, fluid rheology, and multiphysics phenomena—including thermal, chemical, electrical, and mechanical effects. These coupled processes introduce significant challenges during both processing and post-manufacturing stages, which are often difficult to resolve using traditional (experimental) trial-and-error approaches. This review explores the potential of advanced numerical methods and simulation frameworks to address these complexities. Emphasis is placed on the use of finite element and finite volume methods, along with their respective solution strategies and domain discretisation techniques, to solve the coupled governing equations involved in composite manufacturing processes. By integrating theory, computation, and physics-based understanding, these approaches enable predictive capability and design optimisation in the development of high-performance composite components for aerospace applications; many challenges though still remain in fabrication, design, and analysis. Full article

Wave deformation and sediment transport nearest the shoreside are among the main reasons for sand erosion and beach profile changes. In particular, identifying the areas of incident-wave breaking and longshore current generation parallel to the shoreline is important for understanding the morphological changes of coastal beaches. In this study, a two-phase incompressible flow model along with a sandy sloping topography was employed to investigate the wave deformation and longshore current generation areas in a circular wave basin model. The finite volume method (FVM) was implemented to discretize the governing equations in cylindrical coordinates, the volume-of-fluid method (VOF) was adopted to differentiate the air–water interfaces in the control cells, and the zonal embedded grid technique was employed for grid generation in the cylindrical computational domain. The water surface elevations and velocity profiles were measured in different wave conditions, and the measurements showed that the maximum water levels per wave were high and varied between cases, as well as between cross-sections in a single case. Additionally, the mean water levels were lower in the adjacent positions of the approximated wave-breaking zones. The wave-breaking positions varied between cross-sections in a single case, with the incident-wave height, mean water level, and wave-breaking position measurements indicating the influence of downstream flow variation in each cross-section on the sloping topography. The cross-shore velocity profiles became relatively stable over time, while the longshore velocity profiles predominantly moved in the alongshore direction, with smaller fluctuations, particularly during the same time period and in measurement positions near the wave-breaking zone. The computed velocity profiles also varied between cross-sections, and for the velocity profiles along the cross-shore and longshore directions nearest the wave-breaking areas where the downstream flow had minimal influence, it was presumed that there was longshore-current generation in the sloping topography nearest the shoreside. The computed results were compared with the experimental results and we observed similar characteristics for wave profiles in the same wave period case in both models. In the future, further investigations can be conducted using the presented circular wave basin model to investigate the oblique wave deformation and longshore current generation in different sloping and wave conditions. Full article

To improve hydrodynamic conditions and self-purification in plain river networks, this study optimized an existing hydrofoil-based pumping device and redesigned its flow channel. Using the finite volume method (FVM) and overset grid technique, a comparative numerical analysis was conducted on the pumping performance of hydrofoils operating under simple harmonic and quasi-harmonic flapping motions. Based on the tip vortex phenomenon observed at the channel outlet, the flow channel structure was further designed to inform the structural optimization of bionic pumping devices. Results show both modes generate reversed Kármán vortex streets, but the quasi-harmonic mode induces a displacement in vorticity distribution, whereas that of the simple harmonic motion extends farther downstream. Pumping efficiency under simple harmonic motion consistently outperforms that of quasi-harmonic motion, exceeding its peak by 20.2%. The pumping and propulsion efficiencies show a generally positive correlation with the outlet angle of the channel, both reaching their peak when the outlet angle α is −10°. Compared to an outlet angle of 0°, an outlet angle of −10° results in an 8.5% increase in pumping efficiency and a 10.2% increase in propulsion efficiency. Full article

River bends and confluences are critical features in fluvial environments where complex flow patterns, including secondary currents, turbulence, and surface changes, strongly influence sediment transport, river morphology, and water quality. The accurate prediction of these flow characteristics is essential for hydraulic engineering applications. In this study, we present a numerical simulation of turbulent flow in river bends and confluences, with special consideration given to the dynamic interaction between free-surface variations and closed-surface constraints. The simulations were performed using OpenFOAM, an open-source computational fluid dynamics (CFDs) platform, with the k-ω SST (Shear Stress Transport) turbulence model, which is well-suited for capturing boundary layer behavior and complex turbulence structures. The finite volume method (FVM) is used to simulate and examine the behavior of the secondary current in channel bends and confluences. Two sets of experimental data, one with a sharply curved channel and the other with a confluent channel, were used to compare the numerical results and to evaluate the validity of the model. This study focuses on investigating to what extent the k-ω SST turbulence model can capture the effects of secondary flow and surface changes on flow hydrodynamics, analyzing velocity profiles and turbulence effects. The results are validated against experimental data, demonstrating the model’s ability to reasonably replicate flow features under both free- and closed-surface conditions. This study provides insights into the performance of the k-ω SST model in simulating the impact of geometrical constraints on flow regimes, offering a computationally robust and reasonable tool for river engineering and water resources management, particularly in the context of hydraulic structure design and erosion control in curved and confluence regions. Full article

In this study, a novel mechanical fluid–structure interaction (FSI) model is developed to analyze and discuss high-pressure hydrogen flow in a quick coupler under various operating conditions. The transient-state behavior is investigated with respect to different temperatures, hydrogen pressures, and O-ring thicknesses, which directly affect the compression and deformation of the seal. High-pressure hydrogen flow, which may lead to seal damage or failure, is of growing concern due to the increasing use of hydrogen in refueling stations, a sector expected to play a key role in the future of clean energy infrastructure. This study aims to introduce a coupled multiphysics approach by integrating the Finite Element Method (FEM) for solid mechanics with the Finite Volume Method (FVM) for hydrogen flow modeling. The coupling model shows nonlinear interactions between flowing hydrogen and the deformable polymer seal. The results of this work are expected to enhance both the design and performance of high-pressure hydrogen quick couplers, especially for applications in next-generation hydrogen refueling stations, where durability, sealing efficiency and safety are critical. Full article

Various numerical techniques have been developed to address multiple problems in computational fluid dynamics (CFD). The finite volume method (FVM) is a numerical technique used for solving partial differential equations that represent conservation laws by dividing the domain into control volumes and ensuring flux balance at their boundaries. Its conservative characteristics and capability to work with both structured and unstructured grids make it suitable for addressing issues related to fluid flow, heat transfer, and diffusion. This article introduces an FVM for the linear advection and nonlinear Burgers’ equations through a fifth-order targeted essentially non-oscillatory (TENO5) scheme. Numerical experiments showcase the precision and effectiveness of TENO5, emphasizing its benefits for computational fluid dynamics (CFD) simulations. Full article

The process of rock damage and failure is accompanied by the dissipation of energy and an increase in plastic strain. This study attempts to determine the relationship between dissipated energy and plastic strain in sandstone during the damage and failure process. A conventional triaxial cyclic loading and unloading test was conducted on sandstone samples to analyze the energy evolution and plastic strain characteristics of rock during the mechanical performance degradation and deformation failure process. The analysis results indicate that the evolution law of rock energy dissipation and plastic growth during the whole stress–strain process is highly consistent. Before the peak stress, dissipated energy and plastic strain increased linearly with input energy and axial strain, respectively. In the residual stress stage, there is an approximate linear evolution relationship between dissipated energy and plastic strain. Based on the correlation characteristics of energy dissipation and plastic growth, a modified damage model was established by characterizing plastic deformation by damage. In addition, a numerical program was developed using the Finite Volume Method (FVM) based on the damage model. The rock damage model has been validated by experimental results and numerical test. The research findings may provide valuable insights into the correlation mechanism between energy dissipation and plastic growth. Full article

This research aims to study the spray flow of a droplet on an aluminum surface. Fluid spraying is a significant topic in various strategic industries worldwide. In this study, the commercial software FLUENT 22.3.0 is used to simulate the spray of a droplet with turbulent flow on a surface. We use Gambit for mesh generation to ensure accurate and efficient discretization of the computational domain. Initially, we validate our finite volume method (FVM) by comparing the simulation results with existing experimental data to ensure accuracy. After verifying the numerical methods and boundary conditions, we extend the analysis to explore new scenarios involving different environmental pressures, nozzle-to-surface distances, and heated surface temperatures. The effects of pressure variation on the efficiency of droplet heat transfer are examined within sub-atmospheric and super-atmospheric pressure ranges at different Weber numbers, all below the critical Weber number of the droplet. Additionally, by modifying the model geometry and boundary conditions, the influence of the spray-to-surface distance was examined. The findings show that both pressure changes and the spacing between the spray origin and the surface have a substantial effect on the droplet’s heat transfer performance. Full article

This study explores the computational analysis of catalytic combustion in cylindrical reactors using the Finite Volume Method (FVM) within Ansys Fluent. Through the incorporation of a combustion channel to facilitate diesel combustion, Ansys Fluent is utilized to predict the fluid dynamics during catalytic combustion. An extensive reaction mechanism file containing all related reactions is added into Ansys Fluent to model the catalytic combustion of methane. In this study, the catalyzed combustion of a methane, hydrogen, and air mixture is simulated on a heated platinum wall within a cylindrical channel using a 2D axisymmetric solver. Two mechanism files are employed: one defining gaseous species and the other including surface species definitions and surface reactions. Volumetric reactions are excluded from this analysis. The cylindrical channel comprises three sections: inlet, catalytic, and outlet, with the catalyzed reactions occurring on the wall surface of the catalytic section. The simulation results exhibit a gradual decrease in the mass fraction of reactants as catalytic combustion proceeds within the chamber, accompanied by a simultaneous increase in product formation. In particular, the presence of a catalytic channel within the combustion chamber catalyzes the combustion reaction, resulting in a higher chamber temperature. This study also presents predicted mass fraction profiles for both reactants and combustion products, highlighting the efficiency of Computational Fluid Dynamics (CFD) simulations in predicting chemical processes, particularly catalytic combustion. This research contributes to the understanding of complex phenomena such as catalytic combustion and underscores the potential of CFD simulations in explaining complicated chemical processes. Full article