OpenFOAM Computational Fluid Dynamics Research Articles

Thermo-electric modeling and analysis of lithium-ion battery pack for E-mobility

AbstractElectric Vehicles (EVs) have emerged as a viable and environmentally sustainable alternative to traditional internal combustion vehicles by utilizing a clean energy source. The advancement and expansion of electric cars rely on the progress of electrochemical batteries. The utilization of Lithium-Ion Batteries is widespread primarily because of its notable energy density. Changes influence the performance of these batteries in temperature. The Thermal Management System of the battery is one of the very important systems in EVs to improve the performance and life of the battery. The geometrical spacing of the cell modules is considered identical for a more accurate comparison of temperature distribution. For better cooling and heat dissipation, the battery pack’s two sides are kept entirely open to facilitate the inflow of air. In this work, active BTMS solutions are selected and analyzed using the development of three-dimensional free, open-source OpenFOAM computational fluid dynamics simulations for accurate thermal modeling and hotspot zones in cylindrical battery packs. The outcome of the simulations is compared using parameters like temperature distribution in battery cells, battery modules, and heat generation. Among all the cell temperature zones, the temperature maximum is near the sixth cell of the module depth. OpenFOAM results validated with the existing literature’s experimental and Ansys results. Air cooling is utilized for cooling performance because of its relatively simple structure and lightweight.

Multi-Phase flow simulation for transient analysis of ballast drainage behavior and shoulder cleaning effect

This paper presents multi-phase flow simulations to analyze the transient transport of rain droplets through rail ballast and its dependence on fouling conditions and shoulder cleaning. The entire process consisting of random rain droplet injection, droplet migration through the air, falling on the ballast surface, drainage through the void spaces between ballast aggregates, and running off the ballasts are modeled. A computational fluid dynamics (CFD) model is developed, in which the volume of fluid (VOF) method and Darcy-Forchheimer's equation are employed to capture the gas–liquid mixture interface and consider fouling-induced flow resistance, respectively. The model is implemented as an interFoam solver in the OpenFOAM CFD tool. A method for determining trapped moisture inside the fouled and moderately fouled ballast layers is also presented. Parametric simulations are conducted to investigate the effect of fouling conditions, more specifically, Fouling Index (FI), Fouling Profile (FP), and shoulder cleaning on ballasts' drainage performance and time-dependent moisture accumulation and penetration. The results indicate that severe congestion in fouled ballast is responsible for higher moisture accumulation, slower penetration, and poorer drainage of ballast. Shoulder cleaning is an effective measure to reopen flow passage and restore drainage capability, in particular, for the fouled ballast.

Pore-scale simulation of low-salinity waterflooding in mixed-wet systems: effect of corner flow, surface heterogeneity and kinetics of wettability alteration

The initial wettability state of the candidate oil reservoirs for low-salinity waterflooding (LSWF) is commonly characterized as mixed-wet. In mixed-wet systems, both the two-phase flow dynamics and the salt transport are significantly influenced by the corner flow of the wetting phase. Thus this study aims at comprehensive evaluation of LSWF efficiency by capturing the effect of corner flow and non-uniform wettability distribution. In this regard, direct numerical simulations under capillary-dominated flow regime were performed using the OpenFOAM Computational Fluid Dynamics toolbox. The results indicate that corner flow results in the transport of low-salinity water ahead of the primary fluid front and triggers a transition in the flow regime from a piston-like to multi-directional displacement. This then makes a substantial difference of 22% in the ultimate oil recovery factors between the 2D and quasi-3D models. Furthermore, the interplay of solute transport through corners and wettability alteration kinetics can lead to a new oil trapping mechanism, not reported in the literature, that diminishes LSWF efficiency. While the findings of this study elucidate that LSWF does exhibit improved oil recovery compared to high-salinity waterflooding, the complicating phenomena in mixed-wet systems can significantly affect the efficiency of this method and make it less successful.

Electro-thermal performance evaluation of a prismatic battery pack for an electric vehicle

Abstract In recent years, electric vehicles (EVs) have grown in popularity as a viable way to reduce greenhouse gas emissions by replacing conventional vehicles. The need for EV batteries is steadily increasing. An essential and expensive part of electric transportation is the battery. The operating temperature of the lithium-ion (Li-ion) battery significantly impacts the performance of the EV battery pack. Battery packs undergo temperature fluctuations during the charging and discharging procedures due to internal heat generation, necessitating an examination of the temperature distribution of the battery pack. The geometrical spacing between cells is considered larger and identical and is kept open on two sides for free air circulation. A novel battery thermal management system (BTMS) design is required to effectively dissipate heat from the prismatic battery pack module. The electro-thermal behaviour of the prismatic Li-ion battery pack module was investigated based on the high charge/discharge rate. This study presents the development of a three-dimensional free open-source OpenFOAM computational fluid dynamics model for prismatic cell battery packs that simulates heat generation, air flow field, and temperature distribution across the width and depth of the battery pack module. The prismatic battery pack simulation results are compared with the experimental and simulation results of the cylindrical battery pack. It was also revealed that prismatic cells generate more heat on the backside, requiring battery packs to have increased cooling and space between individual cells to ensure sufficient air circulation for cooling and gas removal. The BTMS is improved by designing with increased space among the prismatic battery cells as compared with the conventional prismatic cell battery pack design.

Validation of computational fluid dynamics of shake flask experiments at moderate viscosity by liquid distributions and volumetric power inputs

Computational fluid dynamics (CFD) has recently become a pivotal tool in the design and scale-up of bioprocesses. While CFD has been extensively utilized for stirred tank reactors (STRs), there exists a relatively limited body of literature focusing on CFD applications for shake flasks, almost exclusively concentrated on fluids at waterlike viscosity. The importance of CFD model validation cannot be overstated. While techniques to elucidate the internal flow field are necessary for model validation in STRs, the liquid distribution, caused by the orbital shaking motion of shake flasks, can be exploited for model validation. An OpenFOAM CFD model for shake flasks has been established. Calculated liquid distributions were compared to suitable, previously published experimental data. Across a broad range of shaking conditions, at waterlike and moderate viscosity (16.7 mPa∙s), the CFD model's liquid distributions align excellently with the experimental data, in terms of overall shape and position of the liquid relative to the direction of the centrifugal force. Additionally, the CFD model was used to calculate the volumetric power input, based on the energy dissipation. Depending on the shaking conditions, the computed volumetric power inputs range from 0.1 to 7 kW/m3 and differed on average by 0.01 kW/m3 from measured literature data.

Laser-machined two-stage nozzle optimised for laser wakefield acceleration

In this paper, the modelling and manufacturing of a two-stage supersonic gas jet nozzle enabling the formation of adaptive plasma concentration profiles for injection and acceleration of electrons using few-cycle laser beams are presented. The stages are modelled using the rhoSimpleFoam algorithm of the OpenFOAM computational fluid dynamics software. The first 200–300 ${\rm \mu}$ m diameter nozzle stage is dedicated to 1 % N2 + He gas jet formation and electron injection. By varying the pressure between the first and second stages of the injectors, the electron injection location could be adjusted, and the maximum acceleration distance could be ensured. By changing the concentration of the nitrogen in the gas mixture, the charge of the accelerated electrons could be controlled. The second nozzle stage is designed for acceleration in fully ionised He or hydrogen gas and forms the optimal plasma concentration for bubble formation depending on the laser pulse energy, duration and focused beam diameter. In order to reduce the diameter of the plasma profile formed by the first nozzle and the concentration drop gap between the two nozzles, a one-side straight section was introduced in the first nozzle. The shock wave reflected from the straight section of the wall propagates parallel to the shock wave of the intersecting supersonic jets and ensures a minimal gap between the jets. The second-stage longitudinal plasma concentration profile could have an increasing gas density gradient to compensate for dephasing between the electron bunch and the plasma wave due to wave shortening with increasing plasma concentration.

Numerical study of motorbike aerodynamic wing kit

Abstract This study aims to design the configuration of an aerodynamic wing kit (AWK) on a racing motorbike to achieve the highest downforce-to-drag ratio. The numerical study involves a motorbike traveling in a straight line, where the AWK improves performance and safety by generating downforce to prevent lift. The geometry of the AWK uses a NACA 4412 airfoil with a span of 0.6 m. The computational mesh is generated using SnappyHexMesh and installed on a simplified motorbike to minimize the mesh skewness. The Navier–Stokes equations are solved with OpenFOAM computational fluid dynamics using the Reynolds-averaged Navier–Stokes k-ω SST and large eddy simulation (LES) turbulence models. Case 1 compares a motorbike with and without a dummy, both equipped with the AWK, varying the angle of attack (AoA) from 0 to −41°. Case 2 studies the single wing at different wind speeds (i.e. 20, 60 and 100 m/s) to determine the highest downforce-to-drag ratio at an AoA of −37°. These results serve as the basis for Case 3, which investigates non-parallel wing configurations with a fixed upper wing and a rotating lower wing. In Case 4, where both upper and lower wings rotate simultaneously as parallel wings, the peak downforce-to-drag ratio occurs at an AoA of −41°. Finally, Case 5 modifies the AoA of −41° of the parallel wing of Case 4 to a closed-wing version to comply with Fédération Internationale de Motocyclisme safety regulations. With the LES turbulence model, unsteady and complex turbulence structures can be visualized using the Q-criterion. A comparison of the time-averaged lift coefficient between the wingless and closed-wing configurations shows an increase in downforce of approximately 360%. Subsequently, the popularity of AWK will contribute to the safety of racing motorbike driving.

Computational study of a high-pressure hydrogen storage tank explosion at different heights from the ground

A computational study was carried out to investigate the explosion of a 35-MPa, 72.4-L high-pressure hydrogen storage tank at different heights from the ground. The numerical simulations were carried out using OpenFOAM computational fluid dynamics code. The numerical simulation incorporates a k−ω shear stress transport turbulence model and an eddy dissipation concept combustion model with a one-step finite rate reaction. The prediction performance of the numerical approach was validated based on experimental results obtained from previous studies. The hydrogen tank explosion was investigated at different heights (h; 0.0, 0.2, 0.5, 0.8, and 1.0 m) from the ground and at h = 0.2 m from the ground with θ = 65°). The numerical predictions showed that tank height and position significantly affect the blast overpressure strength and propagation. The reflected pressure magnitude increased as the tank height decreased with respect to ground level. At farther distances, the explosion scenario of h = 0.2 m and θ = 65° showed stronger maximum overpressure and impulse hazards than the other height settings. The difference in maximum overpressure magnitude between the different explosion scenarios was insignificant at 4 m from the tank. Hydrogen gas auto-ignites closer to the ground, due to the compression effect attributed to the Mach stem phenomenon. Our results showed that blast effects in the radial direction are more hazardous than those in the axial direction.

Deciphering the influence of shape on vortex-induced vibrations: Insight from diamond and equilateral triangle cylinder simulations

In this study, we present a comprehensive numerical investigation on the impact of geometric shapes on vortex-induced vibrations (VIV). We deploy the OpenFOAM computational fluid dynamics toolbox to simulate undamped transverse flow-induced vibrations in diamond and equilateral triangular cylinders, operating at a Reynolds number of 100 in a uniform flow. Both cylinders possess an identical mass ratio of 10 and operate within a reduced velocity range of 1–13. Our findings reveal a substantial shift in VIV branching behavior when transitioning from a diamond to a triangular geometry, with both cylinders exhibiting solely VIV responses. Intriguingly, the triangular cylinder does not exhibit a lock-out feature. Furthermore, the triangular cylinder showcases rich dynamical behavior, the occurrence of beating. Coinciding with this geometric transition is a surge in fluid forces and heightened flow asymmetry. While the diamond cylinder predominantly exhibits the P + S mode of vortex shedding, the triangular cylinder displays an unconventional 2P vortex arrangement, contributing to the observed asymmetry. As the geometry transitions from diamond to triangular, we note a phase alignment between the lift and transverse displacement. Remarkably, the triangular cylinder exhibits a higher energy conversion efficiency than its diamond counterpart. This research underscores the significant influence of geometry on vortex-induced vibrations, providing pivotal insight for optimizing the design and performance of structures subjected to fluid flows.

Combining field observations and high-resolution numerical modeling to demonstrate the effect of coral reef roughness on turbulence and its implications for reef restoration design

Coral reefs are effective natural barriers that protect adjacent coastal communities from hazards such as erosion and storm-induced flooding. However, the degradation of coral reefs compromises their ability to protect against these hazards, making degraded reefs a target for restoration. There have been limited field and numerical modeling studies conducted to understand how an increase in coral reef roughness, as would occur due to restoration, can affect wave energy dissipation for a range of real-world wave and water level conditions. To address this knowledge gap, field measurements were collected over adjacent low-roughness and high-roughness reefs off Molokaʻi, Hawaiʻi, USA, subjected to the same oceanographic forcing. Those field data were then used to calibrate and validate OpenFOAM computational fluid dynamics models of the reef. These calibrated models were then used to explore energy dissipation for a range of wave conditions based on measurements from a suite of existing datasets and values from the literature. In general, wave dissipation scales with incident wave conditions, where greater dissipation occurred for shallow depths and shorter-period waves. This tendency for short-period waves to be more readily attenuated is supported by wave energy dissipation factors in the range of 0.1–5, which decline with increasing wave period. Near-bed turbulent kinetic energy dissipation also scales with incident wave conditions, where the greatest difference in dissipation between low and high relief cases occurs for short wave periods. Turbulence becomes less affected by bottom roughness as the wave period increases. Based on this study, wave attenuation and turbulent energy dissipation could be enhanced by 0.5–1 order of magnitude (45% per across-shore meter) if the seabed roughness at the field site were increased by 13%, an achievable goal in coral reef restoration.

Favorable trade-off between heat transfer and pressure drop in 3D printed baffled logpile catalyst structures

Additive manufacturing has the potential to unlock a large degree of geometric freedom in the shaping of catalytic material, thereby providing new possibilities to optimize catalyst holdup, pressure drop and heat and mass transfer characteristics. In this modelling study, baffled logpile structures are proposed as a promising candidate to exploit this potential, by shaping the catalytic material as a static mixer, generating cross-flow. An OpenFOAM Computational Fluid Dynamics study was performed on various 2D structure designs to map the trade-off between heat transfer, pressure drop and residence time distribution as a function of the design, length and gap spacing of the baffle. It is observed that structures with the longest baffles provide optimal heat transfer performance, and that the baffle gap spacing can be used to tailor the trade-off between heat transfer and pressure drop. In comparison to a packed bed filled with spherical particles, the novel structures offer a heat transfer rate four to six times as high at the same pressure drop. Whilst full 3D simulations, validated by experiments, remain to complete the analysis, the current work illustrates the potential of this novel class of structured catalyst materials for intensified chemical reactors.

Large eddy simulation of sneeze plumes and particles in a poorly ventilated outdoor air condition: A case study of the University of Houston main campus

Since the outbreak of the COVID-19 pandemic, many previous studies using computational fluid dynamics (CFD) have focused on the dynamics of air masses, which are believed to be the carriers of respiratory diseases, in enclosed indoor environments. Although outdoor air may seem to provide smaller exposure risks, it may not necessarily offer adequate ventilation that varies with different micro-climate settings. To comprehensively assess the fluid dynamics in outdoor environments and the efficiency of outdoor ventilation, we simulated the outdoor transmission of a sneeze plume in “hot spots” or areas in which the air is not quickly ventilated. We began by simulating the airflow over buildings at the University of Houston using an OpenFOAM computational fluid dynamics solver that utilized the 2019 seasonal atmospheric velocity profile from an on-site station. Next, we calculated the length of time an existing fluid is replaced by new fresh air in the domain by defining a new variable and selecting the hot spots. Finally, we conducted a large-eddy simulation of a sneeze in outdoor conditions and then simulated a sneeze plume and particles in a hot spot. The results show that fresh incoming air takes as long as 1000 s to ventilate the hot spot area in some specific regions on campus. We also found that even the slightest upward wind causes a sneeze plume to dissipate almost instantaneously at lower elevations. However, downward wind provides a stable condition for the plume, and forward wind can carry a plume even beyond six feet, the recommended social distance for preventing infection. Additionally, the simulation of sneeze droplets shows that the majority of the particles adhered to the ground or body immediately, and airborne particles can be transported more than six feet, even in a minimal amount of ambient air.

Design of a Fast Molten Salt Reactor for Space Nuclear Electric Propulsion

The French National Center for Scientific Research (CNRS) is carrying out design studies on a nuclear electric propulsion (NEP) engine based on a molten salt reactor (MSR). A NEP engine based on liquid nuclear fuel could allow developing a core design with relatively high power densities and temperatures while using simple reactivity control systems and keeping low pressure and temperature gradients in the fuel. Nevertheless, the design work of such an engine poses significant technical challenges and requires the use of advanced numerical simulation tools. Different MSRs for space are currently being studied. In this work, a MSR concept using a fast neutron spectrum is investigated using a multiphysics tool based on a numerical coupling between the OpenFOAM (computational fluid dynamics) and SERPENT 2 (Monte Carlo neutronics) codes. The analysis of this paper is focused on the reactor core coupled neutronic and thermal-hydraulic phenomena. Steady state full-power conditions are calculated for two different fast MSR designs using low-enriched uranium (LEU) and highly enriched uranium. The results show that the proposed core layout and materials allow obtaining a satisfactory temperature distribution in the core (maximal values and gradients) without significant penalization of the reactor operating conditions. A reactivity control strategy excluding the use of control rods is studied for the LEU concept. Transient and safety studies are also performed and show acceptable performance.

Simulations of Wind Formation in Idealised Mountain–Valley Systems Using OpenFOAM

An OpenFOAM computational fluid dynamics model setup is proposed for simulating thermally driven winds in mountain–valley systems. As a first step, the choice of Reynolds Averaged Navier–Stokes k−ε turbulence model is validated on a 3D geometry by comparing its results vs. large-eddy simulations reported in the literature. Then, a numerical model of an idealised 2D mountain–valley system with mountain slope angle of 20° is developed to simulate thermally driven winds. A couple of top surface boundary conditions (BC) and various combinations of temperature initial conditions (IC) are tested. A transient solver for buoyant, turbulent flow of incompressible fluids is used. Contrary to classical approaches where buoyancy is set as a variable of the problem, here temperature linearly dependent with altitude is imposed as BC on the slope and successfully leads to thermally driven wind generation. The minimum fluid domain height needed to properly simulate the thermally driven winds and the effects of the different setups on the results are discussed. Slip wall BC on the top surface of the fluid domain and uniform temperature IC are found to be the most adequate choices. Finally, valleys with different widths are simulated to see how the mountain–valley geometry affects the flow behaviour, both for anabatic (daytime, up-slope) and katabatic (nighttime, down-slope) winds. The simulations correctly reproduce the acceleration and deceleration of the flow along the slope. Increasing the valley width does not significantly affect the magnitude of the thermally driven wind but does produce a displacement of the generated convective cell.

Simulation study of fuel spray dynamics in a constant volume combustion chamber

ABSTRACT The OpenFOAM computational fluid dynamics code was used to investigate the performance characteristics of spray jet in a constant volume combustion bomb. The total duration of fuel spray was approximately second, and the total mass of fuel sprayed was kilogram. The results show that there was a positive and somewhat positive qualitative correlation between the profiles of the number of parcels and the mass flow rate of the injected fuel at between second. Furthermore, at between the number of parcels experienced a sharp rise while the injected mass flow rate was decreasing, see Figure 6. The results of the present study show that the spray droplet sizes vary from to which were found to be reasonably representative of measurement data that are usually observed at the top dead centre position of internal combustion engine test bed experiments. Furthermore, the results of the study show the contour plots of pressure and temperature. The pressure rise varies from the initial value of 50 bar to 75 bar at the end of combustion while the temperature rose from to its final value of . The specific details of the results from this study are summarised in the conclusion section.

An efficient methodology for the simulation of nonlinear irregular waves in computational fluid dynamics solvers based on the high order spectral method with an application with OpenFOAM

An efficient methodology for simulating nonlinear irregular waves in a Computational Fluid Dynamics (CFD) solver is proposed. The High Order Spectral (HOS) method is used to generate nonlinear irregular waves in an open ocean and a numerical wave tank. The inverse Fast Fourier Transforms (FFTs) and multi-dimensional interpolation from the HOS simulation results are used for the efficient reconstruction of nonlinear waves in the CFD solver. The proposed procedure is published as an open-source project called Grid2Grid, which is developed to interface with a generic CFD solver. It provides the function Application Programming Interface (API), which can communicate with different programming languages. Extreme wave events were used to validate the proposed procedure. The predicted wave breaking events are reported both in OpenFOAM CFD and HOS simulations, and the wave elevations of CFD during simulations show good agreement with experiments and with HOS simulation.

Computational analysis in underexpanded jets simulations

Flammable gases leaks at high pressures are hazardous, especially the free underexpanded jets. Therefore, understanding their behavior is fundamental to guarantee a safe environment. Due to the difficulty to obtain experimental data from free under expanded jets, related to the great speeds and gradients, computational fluid dynamics (CFD) has become an essential tool. Simulations for free underexpanded jets to identify algorithms that better represent this problem were performed in this work. The analysis involved different algorithms for fluid flow solution and a local time stepping approach using both OpenFOAM and ANSYS Fluent CFD packages. Our study concluded that all algorithms and software studied had a satisfactory result compared to experimental data. However, we observed that Fluent had a considerable advantage because the simulation was faster compared with other solvers in OpenFOAM, for instance.

Accelerating reactive-flow simulations using vectorized chemistry integration

The high cost of chemistry integration is a significant computational bottleneck for realistic reactive-flow simulations using operator splitting. Here we present a methodology to accelerate the solution of the chemical kinetic ordinary differential equations using single-instruction, multiple-data vector processing on CPUs using the OpenCL framework. First, we compared several vectorized integration algorithms using chemical kinetic source terms and analytical Jacobians from the pyJac software against a widely used integration code, CVODEs. Next, we extended the OpenFOAM computational fluid dynamics library to incorporate the vectorized solvers, and we compared the accuracy of a fourth-order linearly implicit integrator–both in vectorized form and a corresponding method native to OpenFOAM—with the community standard chemical kinetics library Cantera. We then applied our methodology to a variety of chemical kinetic models, turbulent intensities, and simulation scales to examine a range of engineering and scientific scale problems, including (pseudo) steady-state as well as time-dependent Reynolds-averaged Navier–Stokes simulations of the Sandia flame D and the Volvo Flygmotor bluff-body stabilized, premixed flame. Subsequently, we compared the performance of the vectorized and native OpenFOAM integrators over the studied models and simulations and found that our vectorized approach performs up to 33–35× faster than the native OpenFOAM solver with high accuracy.

Validation of CFD determined hydrodynamic coefficients for a semisubmersible floating offshore wind turbine

The hydrodynamic characteristics are crucial for accurately analysing floating offshore wind systems. In this paper, the added mass and damping coefficients of a semisubmersible floater are examined around the natural periods of the surge, heave, and pitch motion, using computational fluid dynamics (CFD). The OpenFOAM CFD setup is validated against experimental measurements from the free decay tests, and the same setup is used to determine the hydrodynamic coefficients of the platform subjected to forced motions with different amplitudes and periods. The added mass and quadratic damping coefficients obtained from forced oscillations are consistent with the free decay results. Moreover, the added mass coefficients obtained by CFD is significantly higher than the estimations of the potential flow theory: around 10% larger for surge and 22% larger for heave. The damping is almost independent of the frequency while it varies with the motion amplitude. The deviations in the CFD results from the potential flow theory are due to the viscous effects. Besides, viscous damping is dependent on the drag coefficient specified in the Morison’s equation.

Numerical Simulation and Experimental Study of the Drop Impact for a Multiphase System Formed by Two Immiscible Fluids.

The multiphase splash phenomenon is especially interesting in the context of environmental protection, as it could be a mechanism for transporting various types of pollution. A numerical 3D multiphase transport model was applied to a splash that occurred under the impact of a petrol drop on the water surface. The splash phenomenon in immiscible liquids was simulated using the multiphaseInterFoam solver, i.e., a part of the OpenFOAM computational fluid dynamics software implementing the finite volume method (FVM) for space discretization. Thirteen variants with a variable drop size (3.00–3.60 mm) or drop velocity (3.29–3.44 m/s) were conducted and validated experimentally based on splash images taken by a high-speed camera (2800 fps). Based on the numerical simulation, it was possible to analyse aspects that were difficult or impossible to achieve experimentally due to the limitations of the image analysis method. The aspects included the cavity spread, the jet forming moment, and, notably, the scale of the petroleum contamination spread in the splash effect. The simulations showed that droplets detaching from the crown did not consist of pure water but were mostly a “mixture” of water and petrol or petrol alone. The applied modelling workflow is an efficient way to simulate three-phase splash phenomena.