Influence Of Convection Research Articles

Experimental design and verification of heat transfer flow in a scaled cabin model under the influence of convective and radiative coupling

With the development of aircraft towards high altitude, high speed, and long endurance, the influence of aerodynamic and radiant heat on the flow and heat transfer in the cabin has increased. To explore the flow conditions in the cabin under the influence of ventilation, convection, and radiation coupling, a scaled model test was conducted for verification and simulation. According to the scaling principle, a small ventilation box with a scale of 1: 5 was designed to simulate the boundary conditions in grid computing methods by building ventilation, heating, and irradiation systems. The CFD results were compared with experimental results for analysis. The results show that the experimental results of the scaled model are comparable to the flow field of the prototype model, and the experimental measurement data can be used as a reference indicator for evaluating the temperature field inside the model cabin. The comparison between the simulation experiment and the simulation results verifies the applicability of numerical calculation methods to simulate the flow field in the passenger compartment and the rationality of the scaled test technical scheme.

Investigating the influence of rotating magnetic field (RMF) on intermetallic compound crystallization, thermal and mechanical properties in lead-free Sn-Ag-Cu solder alloys during solidification

This research delves into the effectiveness of using rotating magnetic field (RMF) during the solidification process of Sn-3.5 wt% Ag-0.7 wt% Cu (SAC 357) alloy. The main goal is to evaluate the effect of RMF on the crystallization of intermetallic compounds (IMCs), as well as to study its implications for the thermal properties and creep resistance of the resulting alloy. It is found that the application of the RMF has a significant promotion effect on the improvement in the grain structure of the primary AgSn phase within the directionally solidified SAC 357 alloy. With the application of RMF, the morphology of the primary AgSn phase transformed from developed dendritic-like to fine needle-like, accompanied by a decrease in grain size, but shows no discernible impact on their composition. This observation is attributed to the influence of Lorentz force and thermo-electromagnetic convection. The implementation of a rotating magnetic field (RMF) resulted in notable enhancements in the thermal properties of the SAC357 solder alloy. Specifically, RMF application led to reductions in both the pasty range and melting temperatures, accompanied by a decrease in undercooling compared to conditions without stirring.The SAC357 alloy, when modified with a magnetic field, demonstrated the longest creep rupture time and higher creep resistance compared to those not subjected to magnetic field modification. This research endeavor aims to address a notable gap in our understanding concerning the behavior of SAC357 solder alloys when subjected to a Rotating Magnetic Field (RMF).

The Impact of In-Flight Acceleration Environments on the Performance of a Phase-Change Heat Exchanger Unit with Layered Porous Media

The Phase-Change Heat Exchanger Unit in Layered Porous Media (PCEU-LPM) is obtained through frozen pouring processing, and exhibits characteristics such as high thermal conductivity, high latent heat, and high permeability, making it suitable for dissipating heat in airborne electronic devices. This study numerically investigates the impact of aircraft speed acceleration conditions, which lead to weightlessness or overload, on the performance of the PCHEU-LPM, with a particular focus on the influence of natural convection in the liquid-phase region. Initially, a microscale thermal analysis model is established based on the Navier–Stokes equation scanning electron micrograph to calculate the effective thermal conductivity and permeability of the PCHEU-LPM under different porosities. Subsequently, these parameters are incorporated into a macroscale thermal analysis model based on Darcy’s law, employing an average parameter approach. Using the macroscale thermal analysis model, temperature and velocity fields are computed under various porosities, acceleration magnitudes, and directions. The calculation results indicate that as the acceleration increases from α = 0 to α = 10 g, the interface temperature of the PCHTU-LPM decreases by approximately 5.2 K, and the temperature fluctuation decreases by 2.4 K. If the porosity of the PCHTU-LPM is increased from ε = 70% to ε = 85%, the influence of acceleration change on natural convection will be further amplified, resulting in a decrease in the interface temperature of the PCHTU-LPM by approximately 10.2 K and a decrease in temperature fluctuation by 5.8 K. When the acceleration direction is +z, the interface temperature of the PCHTU-LPM is at its lowest, while it is highest when the acceleration direction is −z, with a maximum difference of 15.4 K between the two. When the acceleration direction is ±x and ±y, the interface temperature lies between the former two cases, with the interface temperature slightly higher for ±y compared to ±x, with a maximum difference of 3.9 K between them.

Study on solid‐air dendrite growth and motion with thermosolutal convection‐diffusion using non‐isothermal PF‐PSLBM model

AbstractThis study unveils a numerical paradigm that amalgamates the partially saturated lattice Boltzmann method (PSLBM) with the non‐isothermal quantitative phase‐field (PF) model. This innovative integration equips us with a prognostic tool ready to elucidate the progression and motion of solid‐air dendritic growth in the presence of both natural and forced convection. The PSLBM is employed to compute the flow of the solution and the interaction forces between the fluid and solid dendrites. Concurrently, the PF model is utilized to simulate the formation of solid‐air dendrites. The reliability of calculating of interaction forces between the fluid and solid was confirmed through a numerical case study involving fluid flow around a stationary cylinder. The results indicate that this model is applicable for simulating the growth and evolution of single/multiple solid‐air dendrites under the influence of convection, whether they are stationary or in motion. The promotion of the upstream side dendritic arms and the inhibition of the downstream dendritic arms increase with the intensification of natural convection. As the initial undercooling is raised, the capacity of natural convection to reshape dendritic morphology gradually diminishes. With the enhancement of forced convection intensity, due to alterations in the flow pattern, the downstream dendritic arms do not consistently exhibit growth suppression. The motion of solid‐air dendrites induced by forced convection counteracts the influence of convection, resulting in slightly faster growth of the downstream dendritic arms compared to the upstream arms. Simultaneously, it fosters the formation of secondary dendritic branches in the upstream zone.

Optimizing entropy in mixed convective MHD dissipative nanofluid with cross-diffusion and nonlinear velocity slip

Entropy optimization is crucial for enhancing fluid dynamics and heat transfer, leading to improved efficiency, energy conservation, and environmental sustainability. Recognizing its significance, we examine the influence of radiation, Joule heating, heat sources, mixed convection, and nonlinear slip on the entropy-optimized flow of a dissipative nanofluid over a curved surface. To seamlessly integrate within the MATLAB bvp4c framework, we convert the set of multi-order ODEs, derived from fundamental PDEs via a similarity transformation approach, into a system of first-order ODEs. Graphs and analytical discussions are used to evaluate the parameters of the problem. The velocity within the boundary layer, along with entropy, experiences reduction due to the enhancement in both first- and second-order slip velocity parameters, as well as curvature parameters. The temperature plot improves with the increase in parameters such as the Soret number and Dufour number, as well as radiation. Conversely, the temperature plot reduces with the rise in suction values. The study indicates that a higher Brinkman number is associated with a lower Bejan number, while the first- and second-order velocity slip parameters have a contrasting effect, leading to an increase in the Bejan number.

A fast fluid–solid coupled heat transfer algorithm based on dividing the development stages of the flow field

In this study, a fast numerical method for solving the forced convection conjugate heat transfer problem was developed. The method first proposes a new dimensionless number (Fs) that represents the degree of influence of convection on the temperature field in the flow field. It delineates the stage of development of the flow field by monitoring the change in Fs to determine the moment when the flow field suspends updating and improve the computational efficiency of the transient temperature field. The accuracy of the algorithm is verified by taking the fluid–solid conjugate heat transfer under forced convection conditions as an example, which can accurately capture the changes of the flow field for a given monitoring step number of 100, and classify the flow field into E3, E4 and E5 development stages according to the judgment criteria. The results show that the higher development stages correspond to smaller levels of root mean square error (RMSE) of monitoring point temperatures within 3600 s of physical simulation time, and stages E3, E4, and E5 can reach the levels of E-2, E-3, and E-4, which are 3.4, 3.3, and 3.1 times faster than the traditional coupled calculations, respectively. The algorithm is still applicable at variable time steps, but it will require a higher number of determinations compared to a fixed step. The initial error of the quasi-steady algorithm can be reduced from the E-1 level to E-4 by choosing a higher stage of development. Finally the algorithm is tested under a variety of conditions by varying the inlet temperature and flow rate and is found to be robust to both device warming and cooling.

Irreversibility analysis of Darcy-Forchheimer flow of a Williamson hybrid nanofluids near a stagnation-point across a vertical plate with buoyancy force

PurposeA novel type of heat transfer fluid known as hybrid nanofluids is used to improve the efficiency of heat exchangers. It is observed from literature evidence that hybrid nanofluids outperform single nanofluids in terms of thermal performance. This study aims to address the stagnation point flow induced by Williamson hybrid nanofluids across a vertical plate. This fluid is drenched under the influence of mixed convection in a Darcy–Forchheimer porous medium with heat source/sink and entropy generation.Design/methodology/approachBy applying the proper similarity transformation, the partial differential equations that represent the leading model of the flow problem are reduced to ordinary differential equations. For the boundary value problem of the fourth-order code (bvp4c), a built-in MATLAB finite difference code is used to tackle the flow problem and carry out the dual numerical solutions.FindingsThe shear stress decreases, but the rate of heat transfer increases because of their greater influence on the permeability parameter and Weissenberg number for both solutions. The ability of hybrid nanofluids to strengthen heat transfer with the incorporation of a porous medium is demonstrated in this study.Practical implicationsThe findings may be highly beneficial in raising the energy efficiency of thermal systems.Originality/valueThe originality of the research lies in the investigation of the Darcy–Forchheimer stagnation point flow of a Williamson hybrid nanofluid across a vertical plate, considering buoyancy forces, which introduces another layer of complexity to the flow problem. This aspect has not been extensively studied before. The results are verified and offer a very favorable balance with the acknowledged papers.

The Influence of the Heat Transfer Mode on the Stability of Foam Extinguishing Agents

The mass loss mechanisms of an aqueous film-forming foam (AF foam), an AR/AFFF water-soluble film-forming foam extinguishing agent (AR foam), and a Class A foam extinguishing agent (A foam) at different levels of thermal radiation, thermal convection, and heat conduction intensity were studied. At a relatively low thermal radiation intensity, the liquid separation rate of the AF, AR, and A foams is related to the properties of the foam itself, such as viscosity and surface/interface tension, which are relatively independent of the external radiation heat flux of the foam. At low radiation intensity (15 kW/m2 and 25 kW/m2), the liquid separation rate of the AF and A foams is relatively stable. When the heat flux intensity is 35 kW/m2, the liquid separation rate of the AF and A foams increases notably, which may be mainly due to the rapid decrease in foam viscosity. And the mass loss behavior is dominated by liquid separation in the AF, AR, and A foams under the influence of thermal radiation and thermal convection. Under the same experimental conditions, the liquid separation rate of AF is the fastest. There is no significant difference in the evaporation rates of the three kinds of foam in the same heat conduction condition. In addition, the AR and A foams usually have a 25% longer liquid separation time (t) under thermal radiation and thermal convection, and the thermal stability is better than AF foam. The temperature reached by the AF foam layer under thermal convection was lower than that of the AR and A foams, and the time for the foam layer to reach the highest temperature under heat conduction was longer than that of the AR and A foams.

Corner melting in low Pr metals: A study using lattice Boltzmann method

Evolution of melting boundary in the solid–liquid phase-change problem involves nonplanar geometry due to the presence of Rayleigh–Benard convective cells in the melted region. The transition of flow behavior from steady to oscillatory in the melt zone is particularly an interesting phenomenon to study. In this work, numerical investigation of melting of low Prandtl number materials in a square cavity with two adjacent heated walls has been carried out using total enthalpy-based lattice Boltzmann method. The local thermal and fluid flow behavior within a moving melting front has been investigated. The influence of natural convection in the melt zone has been observed for two different cases: (1) heating from a corner formed by the left and the bottom walls and (2) heating from a corner formed by the top and the right walls. The effect of Rayleigh number in the range of Ra = 102–5 × 107 on the convective flow field is evaluated for a typical parametric value of Stefan number of 0.01 and Prandtl number of 0.025. Results show distinct convection rolls at the melt zone for the cases under investigations. Evolution of flow fields in the melt zone has been described by a set of isotherms and streamlines for both the cases. The interface fronts for both the cases are initially of convex shape, and around Fourier number of 0.5 turn into concave shape, as viewed from the direction of the movement of melting front. At higher Ra, the rates of melting for top-right side and left-bottom side heated cavities are nearly the same above Fourier number of about 1.2. The average heat flux from the walls scales with Ran , where n is a constant which varies between 0.98 and 1.11. In the melt region, the instability pattern of flow and thermal field changes with the change of effective melt area. Transition to periodic flow is observed at Ra of 7.5 × 106 for case 1 and 2.2 × 107 for case 2, respectively.

Circulating oil-immersed battery thermal management system for cylindrical lithium-ion battery module

Since the lifetime of lithium-ion battery (LIB) is directly related to the operating temperature, it is important to investigate efficient and safe thermal management strategies. This paper mainly studies the effects of pipe position and coolant flow rate on oil-immersed battery thermal management system (BTMS) during circulating cooling. In addition, the theoretical analysis of heat transfer in the 1 C, 1.5 C and 2 C discharge processes is carried out on the oil circulation cooling system. The study found that the temperature of the battery module submerged in the transformer oil dropped by about 34% compared to natural air cooling. In the 9 sets of pipe positions, the inlet and outlet pipeline positions are diagonally distributed, that is, the design of C 4, C 5 and C 6 pipeline positions shows good cooling performance as a whole. Under the condition of high rate discharge, changing the flow rate has a significant impact on the cooling performance of the battery module. The theoretical analysis shows that the influence of forced convection can be ignored in the oil-immersed cooling system at low Re, and with the increasing increase of Re, forced convection dominates the heat transfer of the system. This study provides a new supplement for the process safety of LIB and BTMS applications.

Heat transfer analysis for magnetohydrodynamic peristalsis of Reiner–Philippoff fluid: Application of an artificial neural network

Present communication explores a novel application of the computational intelligence technique, namely, the Levenberg–Marquardt scheme under a Backpropagated Neural Network (LM-BNN) to solve the mathematical model for the magnetohydrodynamic peristaltic transport of Reiner–Philippoff (R–Ph) pseudoplastic fluid considering the influences of Ohmic heating, mixed convection, and viscous dissipation through a symmetric channel. The R–Ph fluid model is used in this investigation to elucidate the non-Newtonian behavior of the fluid under consideration. The Reiner–Philippoff fluid model delineates the intricate relationship between stress and deformation rate within the fluid. There are a few studies available on the peristaltic transport of the Reiner–Philippoff fluid that do not incorporate Joule heating, mixed convection, and magnetic field effects. Therefore, a novel mathematical model is developed to employ an artificial neural network technique with a different approach that has not been examined before. The governing equations of the problem are simplified using long wavelength and low Reynolds number approximations, and the resulting system is numerically solved using the BVP4c scheme in MATLAB based on the shooting algorithm. Furthermore, a dataset is constructed through the BVP4c technique for the proposed LM-BNN, considering eight scenarios of peristaltic motion of the Reiner–Philippoff fluid model by varying the Bingham number, the Brinkman number, the Grashof number, the R–Ph fluid parameter, and the Hartmann number. The numerical dataset is divided into 15% for testing, 15% for training, and 70% for validation, which are utilized in LM-BNN to analyze the numerical solutions and Levenberg–Marquardt neural networks (LM-NNs) predicted results. The consistency and effectiveness of LM-BNN are validated through regression analysis, stresses at the wall, error histogram, correlation index, heat transfer, and mean squared error based fitness curves, which vary from 10−3→10−11. Variations in several flow parameters affecting temperature and velocity profiles are explained physically through graphs. Additionally, an analysis of heat transfer and stresses at the wall, including absolute errors, is provided through tables. The outcomes reveal that the improving Grashof number and the Hartmann number tend to increase the temperature profile. Tabular results indicate that rates of heat transfer improve when assigning higher values to the Hartmann number, the Brinkman number, and the Grashof number, whereas stresses at the wall decrease for the Reiner–Philippoff fluid parameter and the Bingham number. The error analysis of numerical simulations is a valuable step in determining whether the data obtained are reliable and accurate. In terms of absolute error, the disagreement between numerical solutions and those predicted by LM-NNs is approximately 10−5→10−11. It is clear from this error analysis that LM-NNs predicted results are consistent and reliable.

Evaluation of charging process performance of phase change material enhanced with a partially filled metal matrix: A numerical study

Phase change materials (PCMs) may be employed in thermal energy storage to bridge the gap between supply and demand for energy. The main obstacle to PCMs' broad adoption is their limited heat conductivity, leading to their rates of energy recovery and storage being sluggish. This work focuses on tackling this difficulty by adopting a honeycomb structure to improve the performance of a phase-change material using a two-dimensional numerical simulation of melting time. The thermal behavior of a two-dimensional rectangular thermal storage container with phase change material and a honeycomb structure HCS partly filled in the enclosure was the focus of the studies. The current work compares the thermal behavior during melting in a rectangular cavity filled with (Pure PCM alone, Bottom, and Top HCS configurations) that are exposed to a continuous heat source, both with and without natural convection. The solidification/melting module of the commercial CFD software ‘ANSYS Fluent’, which is based on the enthalpy-porosity model, permits modeling based on a transient calculation, making it feasible to examine the charging process of eicosane. For all three configurations, the evolution of the liquid fraction is represented. The storage unit's thermal performance is improved by the use of partially filled honeycomb structures (HCS), according to numerical findings. The optimal reduction in total melting time is attained through the implementation of a top-HCS arrangement, yielding a significant 11% enhancement when natural convection is neglected, while the inclusion of a honeycomb matrix enables only a 3% improvement for the bottom-HCS configuration. Moreover, outcomes reveal that natural convection minimizes melting time differences between the three studied configurations and expedites the process, notably benefiting the reference configuration compared to the two other scenarios. Furthermore, the outcomes demonstrate that natural convection reduces discrepancies in melting times among the three studied configurations and accelerates the charging process. The influence of natural convection is notably more significant for the reference case.

Heating efficiency of agarose samples doped with magnetic nanoparticles subjected to ultrasonic and magnetic field

Recently, magneto-ultrasound heating of tissue in the presence of magnetic nanoparticles (NPs) has been studied due to its high potential for use in oncological hyperthermia. It has been published that a synergistic effect, generation of additional heat caused by magneto-ultrasonic coupling, was observed in a tissue-mimicking material (TMM) enriched with magnetic NPs. The specific absorption rate (SAR) was determined from the temperature rise measurements in a focus of the ultrasound beam. It is important to use precise measurement methods when considering medical applications, for which there are limitations to the power of each field, resulting from the prevention of biological phenomena dangerous to the patient. This study demonstrates that in magneto-ultrasonic heating SAR can be measured much more accurately if the ultrasonic field is almost uniform. Measurements were performed on TMM containing Fe3O4 NPs with a diameter of approximately 8 nm and superparamagnetic properties. Both, the measurement and simulation results showed that the errors resulting from the inaccuracy of placing the temperature probe are smaller than in the case of the focused ultrasound. At the same time, the temperature increase caused by the ultrasonic field is almost linear and the influence of heat convection on the SAR determination is negligible. The measurements showed that magneto-ultrasonic hyperthermia can provide the desired thermal effect at lower ultrasound powers and magnetic fields compared to ultrasonic or magnetic hyperthermia used alone. No synergy effect was recorded.

Convective thermal losses of long-term underground hot water storage

A case of underground long-term hot water storage is investigated numerically. The study is based on the unsteady two-dimensional Navier-Stokes equations in Boussinesq approximation applied to a closed cavern with time-dependent temperature boundary conditions on the walls. The problem formulated in a vorticity-stream function statement is solved by finite difference method (FDM) for high values of the Rayleigh number and for the Prandtl number of water. Streamlines, velocity and temperature fields are presented graphically for given moments of time. The evolution of the thermocline thickness in the mid-section of the cavern is slow and illustrates that the hot water zone occupies more than the half of the cavern even after 6 months period. The Nusselt number on the walls shows that the convective thermal losses are small and after certain period of time tend to decrease due to the diminished temperature difference at the walls. The influence of the fluid convection on the thermal losses is evaluated quantitatively, showing high seasonal thermal efficiency of the insulated hot water storage.

Analytical simulation of Darcy–Forchheimer flow of hybrid nanofluid through cone with nonlinear heat source and chemical reaction

This paper intends to discuss the hybrid nanofluid flow through a cone in a Darcy–Forchheimer porous media, containing base fluid Methanol (CH3OH), nanoparticles of titanium oxide (TiO2) and copper (Cu). We have examined the flow under the influences of mixed convection, viscous dissipation, chemical reaction, and nonlinear heat source. In hybrid nanofluid flow, viscous dissipation and mixed convection play a crucial role in heat exchangers. By accounting for both mixed convection and viscous dissipation, the addition of nanoparticles into a base fluid improves the transfer of heat and optimizes the performance of the cooling system. Using the laws of conservation, governing equations have been constructed. The flow model is converted using the appropriate similarity transformations from partial differential equations to ordinary differential equations. The homotopy analysis method is used to solve the updated system of equations. When Forchheimer inertial drag parameter is increased, the velocity profile decreases, but it rises when the Darcy number is increased. As the value of exponential heat source parameter rises, the temperature profile increases as well. The result exposes that with an increment in nanoparticle volume fraction, temperature profile also rises but velocity profile decreases.

Bi-directional Forced Convective Stagnation Points Flow of Oldroyd-B Liquid with Joule Heating Effects: A Finite Difference Simulations

The impact of Joule heating for the three-dimensional stagnation point flow of non-Newtonian liquid (namely Oldroyd-B) nanomaterial has been inspected. The influence of mixed convection and the magnetic force is also considered. The flow is induced by the bidirectional stretched surface which moves linearly. The partial differential equations for the developed model are altered into dimensionless statements first. The numerical simulations with the implementation of a finite difference scheme are used for the numerical description. The physical description of parameters is presented against the flow parameters. The results reveal that there is a reverse change in velocity observed for both the relaxation time constant and the retardation constant. Furthermore, the heat transfer rate decreases as the ratio parameter increases. The thickness of the boundary layer increases due to the retardation time and can also be regulated by the application of a magnetic field. An increase in the magnetic parameter leads to an enhancement in temperature and an increase in thermal boundary layer thickness.

Fourth-grade nanofluid model with dissipative and nonlinear radiative properties transported peristaltically via a flexible diverging duct holding a porous media under the influence of concentration and heat convection in an induced magnetic field

The major goal of this work is to give a thorough examination of the effect of double diffusion convection (DDC) in addition to a generated magnetic field on peristaltic movement of fourth-grade nanofluid across a vertical sophisticated asymmetrical microchannel using a nondeformable porous media as a basis for intricate pumping systems inspired by biological processes for hazardous waste. The mathematical formulas pertaining to flow, heat/mass transfer under the influence of viscous dissipation, nonlinear heat radiation, and Joule heating were developed using Buongiorno’s framework for nanofluids with combining the thermophoresis and Brownian motion characteristics. Mathematical analysis has been conducted under the suppositions of an extended wavelength and a relatively small Reynolds number. Magnetic field induced axially, density of current, magnetic force function, thermal characteristics, nanoparticles proportion gradient, an additional stress tensor, pressure gradient, and stream function are all given explicit formulas. The constructed function (ND Solve function) within the Wolfram software (Mathematica) is employed to computationally resolve the ensuing system of coupled nonlinear differential equations. Numerical and pictorial evidence is presented to highlight the significance of different physiological characteristics of flow volumes. Further, contour visualizations and circulation bolus have been used to highlight the trapping phenomena, one of among the most noteworthy peristaltic motion occurrences. The main results showed that, despite the dissolvent concentration and the volume percentage of nanoparticles having the opposite effects, the resistance of a substance to heat is shown to climb as the Soret and Dufour numbers rise. At larger levels of the electromagnetic Reynolds number, Strommer’s number, electric field parameter, and thermal Grashof number, stronger axial induced magnetic fields (IMFs) are also provided.

Entropy generation for stagnation point dissipative hybrid nanofluid flow on a Riga plate with the influence of nonlinear convection using neural network approach

Entropy generation for stagnation point dissipative hybrid nanofluid flow on a Riga plate with the influence of nonlinear convection using neural network approach

GPU parallel computing based on PF-LBM method for simulating dendrites growth under natural convection conditions

This study introduces a GPU-based parallel computing approach that combines the phase-field model (PF) and the lattice Boltzmann model (LBM). By establishing a coupled multiphase field model incorporating physical external fields such as flow field, temperature field, and solute field, the research simulates the growth of single grains and multiple grains under the influence of natural convection. The variations in dendritic morphology, flow field, and solute field during dendritic solidification processes are observed. Initially, the study analyzes the morphology of equiaxed dendrites and the growth patterns of primary dendrites arms under natural convection conditions. The evolution of equiaxed dendrites in single grains and multiple grains under various conditions is investigated. Furthermore, the study explores the impact of different anisotropy strengths on the growth of single grains and multiple grains under natural convection. Notably, a distinct “necking” phenomenon is observed when the anisotropy strength of a single grain is 0.05. In the case of multiple grains, where competition between dendrites is present in addition to the influence of natural convection, a pronounced “necking” phenomenon is evident at an anisotropy strength of 0.03. Moreover, OpenCL parallel technology is designed on the GPU platform to accelerate the solution of the model. The parallelization of the phase-field model coupled with the LBM model on the GPU demonstrates a clear advantage. The parallel computation based on GPU not only exhibits absolute superiority but also shows more significant acceleration effects as the computational domain increases.

Abundance of strontium in the Galactic globular cluster 47 Tuc

Aims. We have determined Sr abundance in a sample of 31 red giant branch stars located in the Galactic globular cluster 47 Tuc with the aim to identify potential differences in the Sr abundance between first population (1P, Na-poor) and second population (2P, Na-rich) stars. Methods. We derived the Na and Sr abundances from the archival spectra obtained with the UVES spectrograph. To do this, we used 1D ATLAS9 model atmospheres and a 1D local thermodynamic equilibrium spectral synthesis method. Particular attention was paid to assessing the potential impact of CN line blending on the obtained Sr abundances. Furthermore, we evaluated the potential influence of convection on the Sr line formation by using 3D hydrodynamical model atmospheres computed with the CO5 BOLD code. Results. Our results suggest a weak correlation between the abundances of Sr and Na. Together with a similar correlation between the abundances of Zr and Na determined in our previous study, our analysis of Sr suggests that polluters that have enriched 2P stars with light elements may have produced some s-process elements as well. The mean Sr abundance determined in 31 red giant branch stars of 47 Tuc is ⟨[Sr/Fe]⟩ = 0.18 ± 0.08 (the error denotes the standard deviation due to the star-to-star abundance scatter). This value is within the range of the Sr abundance variation that is observed in Galactic field stars of similar metallicity. The mean [Sr/Zr] abundance ratio in our sample stars suggests that the two s-process elements could have been synthesized by either low-mass asymptotic giant branch stars (M = 1 − 4 M⊙) or massive (M = 10 − 20 M⊙) fast-rotating (vrot = 200 − 300 km s−1) stars.