Finite Volume Research Articles

Efficiency analysis of discontinuous Galerkin approaches for the application onto quantum Liouville-type equations

AbstractThe simulation of nanodevices is computationally inefficient with current algorithms. The discontinuous Galerkin approach has been demonstrated in the field of computational fluid dynamics to deliver high order accuracy and efficiency due to its reliance on matrix–vector multiplications. Previously, the discontinuous Galerkin approach was successfully used in conjunction with the finite volume technique to solve the Liouville–von Neumann equation in center-mass coordinates and thus simulate nanodevices. To exploit its full potential regarding high-performance computing, this work aims to substitute the aforementioned finite volume technique with the discontinuous Galerkin method. To arrive at the said formalism, a finite element method is implemented as an intermediate step.

Application of Extended Eddy-viscosity and Elliptic-Relaxation Approaches to Turbulent Convective Flow in a Partially Divided Cavity

The paper reports on the numerical turbulence model in predicting mass, momentum and heat transfer in a partially divided cavity heated from the side using buoyancy-extended eddy-viscosity and elliptic relaxation approach with the algebraic expressions for the Reynold stress tensor and turbulent heat flux vector. The CDS (central differencing scheme) and LUDS (linear upwind differencing scheme) were used as the discretization method and the governing equations were solved using the finite volume method and Navier-Stokes solver. Validation of the model has been carried out by experimental data of convective flow in the cavity as well as by numerical data DNS (direct numerical simulation). The model agrees very well with the experiment and DNS and it is also able to demonstrate the performance which is comparable to that of the previous advanced second-moment closure model (SMC) in the literature. The results show that the model is suitable for use in simulations of the turbulent convective flow in a cavity with partition and it has the potential to be applied to more complex cavities and a wide range of turbulence levels.

Enhancing performance in solar air channels: A numerical analysis of turbulent flow and heat transfer with novel shaped baffles

Solar air heaters are emerging as a promising solution for sustainable heating, as they harness abundant solar energy to provide heat for a variety of applications. However, their optimum efficiency remains a major challenge. Deflectors have significant potential to improve the performance of solar air heaters by redirecting airflow and optimizing heat transfer, making them more efficient and more suitable for large-scale adoption. This article examines the performance of a new baffle design aimed at improving heat transfer in the channel by increasing the exchange surface between fluid and solid surface. It consists of a “≠” -shaped baffle mounted on the top and bottom walls of the channel. An in-depth analysis of the spacing between these baffles was carried out to assess their impact on the thermal and aerodynamic properties of the solar air channel. Computational Fluid Dynamics (CFD) was used to perform the calculations, using the Finite Volume Method (FVM) in conjunction with the SIMPLE algorithm. All studies are carried out using the CFD code Fluent. Crucial steps in this research include studying the influence of these new baffles at different Reynolds numbers, ranging from 15000 to 35000, as well as varying the separation distance between the two baffles, chosen periodically (DBaffle/2, 3DBaffle/4, DBaffle, 5DBaffle/4 and 3DBaffle/2). Some of the numerical results were validated with the available experimental data and showed satisfactory agreement. The study identified an optimal case for the new baffles, by reducing the distance between the baffles, an improvement in system performance was observed, by increasing the flow strength and widening the recycling cells, which has an impact on dynamic behavior and heat transfer. The presence of this new baffle design, with minimal separation distance between them, demonstrated a significant thermal improvement, with a thermal improvement factor increasing by 44% compared to the simple channel without baffles, thus highlighting the effectiveness of the new solar air channel with “≠” -shaped baffles.

Thermal management performance of lithium-ion batteries coupled with honeycomb array manifold and phase change materials under microgravity conditions

Absence of natural convection in microgravity brings new challenges to the design of battery heat dissipation and cooling systems, which is key to solving the problems of aerospace thermal control systems. A novel model is proposed to numerically investigate the thermal management performance of lithium-ion batteries coupled with honeycomb array manifold and phase change materials (PCM) under microgravity conditions. Compared with traditional battery thermal management system (BTMS), the present study deftly takes advantage of the honeycomb manifold liquid cooling plate to improve the flow distribution and power loss, as well as the isothermal phase transition and energy storage effects of the PCM to better thermal management performance. The finite volume method is used to solve three-dimensional thermal management processes within the hybrid BTMS. Experimental validations are conducted for the heat generation model of battery and the mathematical model of BTMS. Special considerations are shown for the effects of manifold flow structures, inlet and outlet layouts and geometric parameters on cooling performance and energy consumption of BTMS. The numerical results show that PCM coupled with honeycomb array manifold cooling plate of scheme 6 has the advantages of efficient heat dissipation and energy efficiency. The inlet distributed in hexagonal corners of Case 2 has a maximum temperature of about 308 K, which is about 1 K lower than that of Case 1 and its coefficient of performance is about 1.55 times of that of Case 1. For the three cases with TPCM : TC < 1, the variation of pressure drop is within 1.06 %. For the same battery spacing, the ratio of TPCM : TC between 3/7 ∼ 2/3 has better overall performance.

A Vertex-Centered Arbitrary Lagrangian-Eulerian Finite Volume Method with Sub-Cells for Two-Dimensional Compressible Flow

A Vertex-Centered Arbitrary Lagrangian-Eulerian Finite Volume Method with Sub-Cells for Two-Dimensional Compressible Flow

Energy-Preserving Hybrid Asymptotic Augmented Finite Volume Methods for Nonlinear Degenerate Wave Equations

Energy-Preserving Hybrid Asymptotic Augmented Finite Volume Methods for Nonlinear Degenerate Wave Equations

Convergence of the Finite Volume Method for Stochastic Hyperbolic Scalar Conservation Laws: A Proof By Truncation on the Sample-Time Space

Convergence of the Finite Volume Method for Stochastic Hyperbolic Scalar Conservation Laws: A Proof By Truncation on the Sample-Time Space

New Finite Volume Mapped Unequal-Sized WENO Scheme for Hyperbolic Conservation Laws

New Finite Volume Mapped Unequal-Sized WENO Scheme for Hyperbolic Conservation Laws

The Positivity-Preserving Finite Volume Coupled with Finite Element Method for the Keller–Segel–Navier–Stokes Model

The Positivity-Preserving Finite Volume Coupled with Finite Element Method for the Keller–Segel–Navier–Stokes Model

A Numerical Study of Integrated Linear Reconstruction for Steady Euler Equations Based on Finite Volume Scheme

A Numerical Study of Integrated Linear Reconstruction for Steady Euler Equations Based on Finite Volume Scheme

Prediction of solidification structure in the laser metal deposition of IN625 superalloy using the numerical and experimental techniques

Extensive research has been conducted in the field of direct laser deposition (DLD) process simulation. In this study, the finite volume method was used to predict the solidification microstructure and melt pool status in the IN625 cladding process. By fitting the data and matching the Hunt-Fleming relationship, the values of a=29.1827 and n=0.354 were obtained. A columnar structure was observed near the G/R=1.4e6 line, a combination of columnar and equiaxed structures between the G/R=1.4e6 and G/R=0.3e6 lines, and a fully equiaxed structure at points below the G/R=0.3e6 line. Finally, using the RSM method, a suitable area for achieving directional solidification (columnar dendrite with minimum orientation), with a power of more than 225 W and a powder/scan speed ratio (F/S) of less than 40 mg/mm, was determined.

Investigating the impact of different solder alloy materials during laser soldering process

Purpose This study aims to investigate the influence of different solder alloy materials on passive devices during laser soldering process. Solder alloy material has been found to significantly influence the solder joint’s quality, such as void formation that can lead to cracks, filling time that affects productivity and fillet shape that determines the solder joint’s reliability. Design/methodology/approach Finite volume method (FVM)-based simulation that was validated using real laser soldering experiment is used to evaluate the effect of various solder alloy materials, including SAC305, SAC387, SAC396 and SAC405 in laser soldering. These solders are commonly used to assemble the pin-through hole (PTH) capacitor onto the printed circuit board. Findings The simulation results show how the void ratio, filling time and flow characteristics of different solder alloy materials affect the quality of the solder joint. The optimal solder alloy is SAC396 due to its low void ratio of 1.95%, fastest filling time (1.3 s) to fill a 98% PTH barrel and excellent flow characteristics. The results give the ideal setting for the parameters that can increase the effectiveness of the laser soldering process, which include reducing filling time from 2.2 s to less than 1.5 s while maintaining a high-quality solder joint with a void ratio of less than 2%. Industries that emphasize reliable soldering and effective joint formation gain the advantage of minimal occurrence of void formation, quick filling time and exceptional flowability offered by this solution. Practical implications This research is expected not only to improve solder joint reliability but also to drive advancements in laser soldering technology, supporting the development of efficient and reliable microelectronics assembly processes for future electronic devices. The optimized laser soldering material will enable the production of superior passive devices, meeting the growing demands of the electronics market for smaller, high-performance electronic products. Originality/value The comparison of different solder alloy materials for PTH capacitor assembly during the laser soldering process has not been reported to date. Additionally, volume of fluid numerical analysis of the quality and reliability of different solder alloy joints has never been conducted on real PTH capacitor assemblies.

Influence of periodicity on natural convection in a square porous cavity due to non-uniform heat under LTNE state

In this article, the influence of the local thermal non-equilibrium (LTNE) state on free convection in a square cavity filled with fluid-saturated porous medium is investigated numerically. The steady-state flow is induced due to sinusoidal heat distributed on the side walls of the cavity and insulated of the horizontal walls. The coupled flow governing equations are solved numerically by using the finite volume method (FVM) consisting of the SIMPLER (Semi-Implicit Method for Pressure Linked Equation Revised) Algorithm. The numerical simulations of temperature and stream-function contours are carried out for the non-Darcy model. The developed code is validated with existing numerical and present computed results for the case of a square enclosure associated with non-uniform heat source. Then, the present numerical results are analyzed over a range of physical parameters, like periodicity parameter ( N ≥ 1 ), interface heat transfer coefficient ( 10 − 2 ≤ H ≤ 10 2 ), porosity scaled thermal conductivity ratio ( 10 − 2 ≤ γ ≤ 10 2 ), with a fixed Rayleigh number ( Ra = 10 6 ), Darcy number ( Da = 10 − 4 ), Prandtl number (Pr = 0.71), and porosity ( ε = 0.8 ). To study the impacts of these key parameters on the fluid flow behavior and isotherm patterns of fluid as well as solid phase in the porous-square enclosure. From present numerical experiments that the structure of flow is controlled by multicellular structure with rotating clockwise and anticlockwise directions in the entire results. The flow dynamics are highly affected by the periodicity parameter (N) under LTNE circumstances. The characteristics of the local Nusselt number have the point of inflection and the maximum magnitude of it increases with N. The significant effect of H is found on the heat transfer rate of fluid phase but it is negligible on the heat transfer rate of solid phase. However, the influence of γ is found reverse in nature on the heat transfer rate of fluid as well as solid phase when as compared to the effect of H.

Energetic particles transport in constants of motion space due to collisions in tokamak plasmas

Abstract The spatio-temporal evolution of the energetic particles in the transport time scale in tokamak plasmas is a key issue of the plasmas confinement, especially in burning plasmas. In order to include sources and sinks and collisional slowing down processes, a new solver, ATEP-3D was implemented to simulate the evolution of the EP distribution in the three-dimensional constants of motion (CoM) space. The Fokker-Planck collision operator represented in the CoM space is derived and numerically calculated. The collision coefficients are averaged over the unperturbed orbits to capture the fundamental properties of EPs. ATEP-3D is fully embedded in ITER IMAS framework and combined with the LIGKA/HAGIS codes. The finite volume method and the implicit Crank-Nicholson scheme are adopted due to their optimal numerical properties for transport time scale studies. ATEP-3D allows the analysis of the particle and power balance with the source and sink during the transport process to evaluate the EP confinement properties.

Multifaceted simulation: Finite volume and finite element modeling of blood flow in multiple stenosed arteries

Cardiovascular illnesses are a primary global health concern because they are frequently brought on by arterial stenosis. The complicated hemodynamics of blood flow via elliptically shaped arteries with numerous stenotic lesions along their top and bottom walls are examined in this paper. Carreau fluid model is used with Navier–Stokes equations in this study. The complete comparative study is done by using the Finite Element and Finite Volume Methods. This study uses commercial software to examine blood flow velocity, pressure and temperature distributions under various physiological situations at Reynolds number 30. Our results illuminate the interaction between flow dynamics, stenosis characteristics, and arterial geometry. The novelty of the work is to investigate how stenosis size, shape, and location affect pressure gradients, and flow disturbances. These observations provide helpful direction for understanding disease progression, designing treatments, and possibly new stent designs. The future direction of this research may involve further exploration of the interplay between hemodynamics and arterial stenosis by incorporating advanced computational models. Additionally, studies focusing on in vivo validation and clinical applications could enhance the translational impact of the findings. Collaborations between researchers, clinicians, and engineers may pave the way for personalized treatment strategies and innovations in cardiovascular care based on a deeper understanding of the intricate dynamics within diseased arteries.

Gauge Field Marginal of an Abelian Higgs Model

We study the gauge field marginal of an Abelian Higgs model with Villain action defined on a 2D lattice in finite volume. Our first main result, which holds for gauge theories on arbitrary finite graphs and does not assume that the structure group is Abelian, is a loop expansion of the Radon–Nikodym derivative of the law of the gauge field marginal with respect to that of the pure gauge theory. This expansion is similar to the one of Seiler (Gauge theories as a problem of constructive quantum field theory and statistical mechanics, volume 159 of lecture notes in physics, Springer, Berlin, p v+192. https://doi.org/10.1007/3-540-11559-5, 1982) but holds in greater generality and uses a different graph theoretic approach. Furthermore, we show ultraviolet stability for the gauge field marginal of the model in a fixed gauge. More specifically, we show that moments of the Hölder–Besov-type norms introduced in Chevyrev (Commun Math Phys 372(3):1027–1058. https://doi.org/10.1007/s00220-019-03567-5, 2019) are bounded uniformly in the lattice spacing. This latter result relies on a quantitative diamagnetic inequality that in turn follows from the loop expansion and elementary properties of Gaussian random variables.

Application of Delaunay adaptive mesh refinement in flood risk assessment of multi-bridge system with short distance

To ensure bridge safety, the flood risk analysis is significant important. However, due to the small size and large number of piers in the short-distance multi-bridge system, the extremely long calculation time and low efficiency of the numerical model are induced by the small mesh size and large mesh number. In this paper, a flood risk assessment model of the multi-bridge system with short distance was established to improve the calculation efficiency based on the finite volume method combined with the Delaunay mesh adaptive refinement method. The calculated water level with refined and non-refined mesh was compared with the experimental data of a partial failure dam break test case and Shukry experiment of open channel bend flow. The calculated water level results are in good agreement with the experimental data. In addition, the mesh refinement model improved the calculation efficiency by more than 73% with ensuring the calculation accuracy. Finally, the flood risk of a real multi-bridge system with short distance was evaluated by using the numerical model. The calculated results shown that, different from the general flow law, the water level in the upstream and downstream channel of Bridge 2 rose with a maximum difference value of 0.326 m while the water level in the far downstream channel of Bridge 2 dropped result from the construction of Bridge 2 on the basis of the Bridges 1, 3 and 4. The construction of Bridge 2 also increased the flow velocity around Bridge 3 with maximum 0.013 m/s. This study provides a new tool and technical reference for flood risk analyses of similar multi-bridge system with short distance.

Optimization Based on Computer Fluid Dynamics Finite Element Method Automotive Cooling Fan Structure

With the continuous improvement of vehicle comprehensive technology, the heat load generated by automotive engine systems, hydraulic systems, and other devices also increases. Therefore, improving the heat dissipation efficiency of the cooling system is a key technology that cannot be ignored in the current vehicle development process. The car cooling fan is an important component of the cooling system, and its working characteristics will directly affect the cooling effect of the engine. This article uses the finite volume method of computer fluid dynamics to optimize the structure of a heat dissipation fan, analyze and define the flow field control volume required for its numerical calculation, use structured and unstructured grids to discretize the internal flow field region, select pressure inlet and pressure outlet boundary conditions, and simulate and analyze the fluid flow in the radiator based on fluid dynamics theory calculations. The orthogonal experimental method was used to analyze various performance indicators during the experimental process. The results showed that the comprehensive performance of the No. 3 optimized cooling fan was the best, with a 10.45% increase in static pressure efficiency, a 14.03% increase in dynamic pressure efficiency, and an 11.26% increase in maximum flow velocity. The optimized fan flow field streamline became more full and uniform, significantly improving the fluid dynamics performance of the air in the cooling system.

New Results for Riemann Solution of the Cargo-LeRoux Model by the Application of Flux-Limiter Schemes

The Rienamm solution of the Cargo-LeRoux model has been recently introduced in [1] in which authors have found the exact solutions to the initial value problem. This work is the first attempt to apply numerical methods for the Cargo-LeRoux model. The higher-order flux limiter method applied in this paper holds the total variation diminishing property and gives smooth solutions in steep gradient regions. Various limiter functions that lead to different accuracy in numerical results are tested for the Riemann problem. The numerical investigations presented in this work can be used to review limiter-based TVD schemes extensively and to construct a class of highly efficient finite volume/ finite difference methods for such models.

Thermo-fluid performance for helical coils inserted in a tube using hybrid CFD-ANN approach

This paper presents a numerical investigation into the thermal performance of helical coils, assessing the impact of spacing, wire diameter ratio, and coil pitch ratio on the pressure drop and heat transfer characteristics. Heat flux was maintained at 1000 W/m2, while Reynolds numbers ranged from 5000 to 30,000. Coil configurations encompassed pitch ratios within 1 ≤ p/d ≤ 3, wire diameter ratios spanning 0.044 ≤ e/d ≤ 0.133, and spacing intervals of 0.5, 1, and 2 mm. The finite volume method was employed to solve the energy, Navier-Stokes, and 3D continuity equations. Results indicate substantial influences of wire diameter, coil pitch ratios, and spacing on Nusselt number friction factors within the coiled tube. Notably, Nusselt number enhancements within the studied intervals ranged from 16 % to 102 %, with an overall performance criteria improvement reaching 43 %. Furthermore, a machine learning approach utilizing artificial neural networks (ANN) was employed, with comparisons drawn between results obtained from the ANN and computational fluid dynamics (CFD). The congruence between experimental, CFD, and ANN findings underscores the reliability of the study outcomes.