International Journal of Numerical Methods for Heat & Fluid Flow最新文献

{"title":"Determining local distribution of convective heat transfer coefficients on the tool during orthogonal cutting","authors":"Julius Wilker, Tim Göttlich, Thorsten Helmig, Rafael Solana Gómez, Hossein Askarizadeh, Reinhold Kneer","doi":"10.1108/hff-08-2024-0638","DOIUrl":"https://doi.org/10.1108/hff-08-2024-0638","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>Particularly during machining, large heat sources and thus high temperature gradients and mechanical stress occur in the cutting zone. By using cutting fluids, part of the heat generated can be dissipated, thereby reducing local temperatures. To quantify the cooling efficiency of the cutting fluid, the flow behaviour of the cutting fluid in vicinity of the cutting zone must be determined to derive the resulting convective heat transfer coefficients at the tool. The purpose of this paper is to investigate the local distribution of the convective heat transfer coefficient as a function of the flow boundary conditions, specifically evaluating the effects of Reynolds number, injection angle and nozzle radius.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>The geometries, temperature fields as well as the heat sources resulting during the machining process are extracted from a chip formation simulation using finite element method (FEM) and used to set up a three-dimensional computational fluid dynamics (CFD) flow simulation.</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>On the tool rake face, the local distribution of the convective heat transfer coefficient can be divided into three regions. Firstly, the region where the liquid impinging jet initially strikes, then a region near the chip where the flow is strongly deflected and then the remaining region in the boundary layer region. For each region, a function is derived that describes its position, subsequently the mean convective heat transfer coefficient is determined and summarised in a Nusselt correlation as a function of the flow parameters.</p><!--/ Abstract__block -->\u0000<h3>Research limitations/implications</h3>\u0000<p>Simulation results reveal that the distribution of the convective heat transfer coefficient on the tool rake face can be divided into three distinct regions: the impingement zone where the impinging jet first strikes, the deflection zone near the chip where the flow sharply redirects and the boundary layer zone covering the remaining surface. A geometric function is derived to describe the position and extent of each of these areas. In addition, the mean convective heat transfer coefficient can be determined for each of the regions using a Nusselt correlation based on the flow parameters.</p><!--/ Abstract__block -->\u0000<h3>Practical implications</h3>\u0000<p>These correlations allow for simplified determination of the local convective heat transfer coefficient on the tool.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>This paper introduces an innovative approach for estimating the local distribution of the convective heat transfer coefficient at the tool rake face during orthogonal cutting under cutting fluid supply. The influence of the three-dimensional flow field of the cutting fluid jet of the convective heat transfer coefficient on the tool rake face is analysed in detail in the vicinity of the chip as a function of varying Rey","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"22 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143462759","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A continuous adjoint cut‐cell formulation for topology optimization of bi‐fluid heat exchangers","authors":"Nikolaos Galanos, Evangelos Papoutsis-Kiachagias, Kyriakos Giannakoglou","doi":"10.1108/hff-08-2024-0642","DOIUrl":"https://doi.org/10.1108/hff-08-2024-0642","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>This paper aims to present a topology optimization (TopO) method for designing heat exchangers (HEx) with two working fluids to be kept apart. The introduction of cut–cells gives rise to the cut-cell TopO method, which computes the optimal distribution of an artificial impermeability field and successfully overcomes the weaknesses of the standard density-based TopO (denTopO) by computing the fluid–solid interface (FSI) at each cycle. This allows to accurately solve the flow and conjugate heat transfer (CHT) problem by imposing exact boundary conditions on the computed FSI and results to correct performances computed without the need to re-evaluate the optimized solutions on a body-fitted grid.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>The elements of an artificial impermeability distribution field defined on a background grid act as the design variables and allow topological changes to take place. Post-processing them yields two fields indicating the location of the two flow streams inside the HEx. At each TopO cycle, the FSIs computed based on these two fields are used as the cutting surfaces of the cut-cell grid. On the so-computed grid, the incompressible Navier–Stokes equations, coupled with the Spalart–Allmaras turbulence model, and the temperature equation are solved. The derivatives of the objective and constraint functions with respect to the design variables of TopO are computed by the continuous adjoint method, using consistent discretization schemes devised thanks to the “Think Discrete – Do Continuous” (TDDC) adjoint methodology.</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>The effectiveness of the cut-cell–based TopO method for designing HEx is demonstrated in 2D parallel/counter flow and 3D counter flow HEx operating under both laminar and turbulent flow conditions. Compared to the standard denTopO, its ability to compute FSIs along which accurate boundary conditions are imposed, increases the accuracy of the flow solver, which usually leads to optimal, rather than sub-optimal, solutions that truly satisfy the imposed constraints.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>This work proposes a new/complete methodology for the TopO of two-fluid systems including CHT that relies on the cut-cell method. This successfully combines aspects from both TopO and Shape Optimization (ShpO) in a single framework thus overcoming the well-known downsides of standard denTopO regarding its accuracy or the need for a follow-up ShpO after TopO. Instead of adding the well-known Brinkman penalization terms into the flow equations, it computes the FSIs at each optimization cycle allowing the solution of the CHT problem on a cut-cell grid.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"12 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Isogeometric boundary element formulation to simulate droplets in microchannel confinement","authors":"Ozgur Can Gumus, Gokberk Kabacaoglu, Barbaros Cetin","doi":"10.1108/hff-08-2024-0641","DOIUrl":"https://doi.org/10.1108/hff-08-2024-0641","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>This study aims to present an isogeometric boundary element formulation that stably and accurately models the motion of a droplet with arbitrary viscosity in free flows and microchannel confinements.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>Like other numerical methods, isogeometric boundary element formulation also suffers from mesh distortion; therefore, volume correction and mesh relaxation are also required for efficient and stable simulations of deformable particles in Stokes flow with high accuracy. To improve the stability and accuracy of the proposed formulation, (i) volume correction and (ii) mesh relaxation algorithms to prevent mesh distortion are implemented.</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>Several test cases for a droplet in free-space shear flow are demonstrated for different Ca and viscosity ratio values which determine the deformability of a droplet. The results reveal that the drift of the enclosed volume inside a droplet and the mesh distortion becomes severe at low viscosity ratios and high Ca values, i.e. in the high deformability regime. The proposed numerical method integrating the stabilization algorithm enables the simulations at low spatiotemporal resolutions, even in extreme cases. The proposed method provides more than 10× speed-up compared to high-fidelity simulations without mesh relaxation. Efficient and accurate 3D simulations of droplets are also presented for simulations in microfluidic confinement.</p><!--/ Abstract__block -->\u0000<h3>Practical implications</h3>\u0000<p>The current formulation can be applied for many different microfluidic applications, and can be extended to tackle multiphysics simulations of multiple droplets in microchannel confinement.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>The paper presents an isogeometric boundary element formulation with volume correction and mesh relaxation to model the motion of a droplet with arbitrary viscosity in free flows and microchannel confinements.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"12 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magnetohydrodynamic ternary hybrid nanofluid slip flow past a permeable shrinking sheet: boundary layer flow control and optimization using response surface methodology","authors":"Nur Syahirah Wahid, Shahirah Abu Bakar, Mohd Shafie Mustafa, Norihan Md Arifin, Ioan Pop","doi":"10.1108/hff-08-2024-0637","DOIUrl":"https://doi.org/10.1108/hff-08-2024-0637","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>Magnetohydrodynamics (MHD) in nanofluids is crucial in boundary layer flow as it enables the manipulation of fluid motion through magnetic fields, which leads to improved stability and efficiency. This study aims to introduce a model and solutions for the boundary layer flow of a ternary hybrid nanofluid past a permeable shrinking sheet, integrating both magnetohydrodynamic and slip effects.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>The model is firstly expressed as partial differential equations and subsequently converted into ordinary differential equations (ODEs) through a similarity transformation technique. A finite difference scheme with the Lobatto IIIa formula in MATLAB is applied to numerically solve the ODEs, where the respective outcomes provide insights into the skin friction coefficient, Nusselt number, velocity profiles and temperature profiles.</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>The results highlight the significance of enhancing magnetohydrodynamic effects and first-order velocity slip to reduce skin friction, improve heat transfer, delay boundary layer separation, increase flow velocity and lower fluid temperature. In addition, the stable numerical solution is scrutinized using response surface methodology (RSM) to validate and optimize flow control. The RSM optimization confirms that higher suction, magnetohydrodynamic effects and first-order slip levels are essential for minimizing skin friction and maximizing heat transfer simultaneously.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>The presented model together with the numerical and statistical results can be used as a guidance to control the flow and heat transfer that occur within a related practical application, especially in engineering and industrial activities such as cooling technologies, energy harvesting or fluid transport in nanotechnology, where precise control of heat transfer and fluid dynamics is essential for optimizing performance and reducing energy consumption.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"193 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143393571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of rotation and voids on reflection of plane waves in a transversely isotropic magneto-thermoelastic half-space under GN-II model","authors":"Reetika Goyal, Sunita Deswal, Kapil Kumar Kalkal","doi":"10.1108/hff-08-2024-0576","DOIUrl":"https://doi.org/10.1108/hff-08-2024-0576","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>In the framework of GN-II theory, this paper aims to address the plane wave propagation in a two-dimensional homogeneous, transversely isotropic magneto-thermoelastic medium with rotation and voids.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>To investigate the problem, the fundamental governing equations are modified in the purview of Green-Naghdi theory without energy dissipation. These equations are converted to non-dimensional form using dimensionless quantities and are further solved to obtain four quasi plane waves travelling with different phase speeds in the considered medium. Amplitude ratios and energy ratios have been provided in explicit form after implementing the proper boundary conditions.</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>Numerical calculations are carried out using MATLAB software. For graphical representation of the expressions for phase velocities, reflection coefficients and energy ratios, a particular material is chosen to demonstrate the effects of magnetic field, rotation and void parameter.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>The reflection coefficients are strongly affected by rotation, void parameter and magnetic field, as evidenced by conceptual and numerical findings. For validation of this study, the outcomes have also been compared to earlier published studies. In addition, it has also been established that the energy conservation law is also justified during the reflection phenomena. In the current research, the authors have included rotation and magnetic field in a transversely isotropic thermoelastic medium having voids, which has not yet been addressed in the published research. The results of current problem are very useful in a number of fields, such as soil dynamics, geophysical processes, chemical engineering and petroleum sector.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"55 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143393572","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploring the impact of morphological nanolayers on mixed convection in MHD nanofluids through a neurocomputational approach","authors":"Faisal, Aroosa Ramzan, Moeed Ahmad, Waseem Abbas","doi":"10.1108/hff-11-2024-0833","DOIUrl":"https://doi.org/10.1108/hff-11-2024-0833","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>This study aims to develop a neurocomputational approach using the Levenberg–Marquardt artificial neural network (LM-ANN) to analyze flow and heat transfer characteristics in mixed convection involving radiative magnetohydrodynamic hybrid nanofluids. The focus is on the influence of morphological nanolayers at the fluid–nanoparticle interface, which significantly impacts coupled heat and mass transfer processes.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>This research simplifies a complex system of higher-order nonlinear coupled partial differential equations governing the flow between orthogonal coaxially porous disks into ordinary differential equations via similarity transformations. These equations are solved using the shooting method, and parametric studies are conducted to observe the impact of varying important parameters. The resulting data sets are used to train, validate and test the LM-ANN model, which ensures high predictive accuracy. Machine learning and curve-fitting techniques further enhance the model’s capability to generate detailed visualizations.</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>The findings of this study indicate that increased nanolayer thickness (0.4–1.6) significantly improves thermal performance, while changes in the chemical reaction parameter (0.2–1) have a notable effect on enhancing the Sherwood number. These results highlight the critical role of morphological nanolayers in optimizing thermal and mass transfer efficiency in MHD nanofluids.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>This research provides a novel neurocomputational framework for understanding the thermal and mass transfer dynamics in MHD nanofluids by incorporating the effects of interfacial nanolayers, an aspect often overlooked in conventional studies. The use of LM-ANN trained on computational data sets enables high-fidelity predictive analysis, offering new insights into the enhancement of thermal and mass transfer efficiency in hybrid nanofluid systems.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"1 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143258740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The effect of lateral position of heating surface and angular orientation of latent heat thermal energy storage system on the melting characteristics: a numerical investigation","authors":"Himanshu Kumar, Gurjeet Singh, Ankit Yadav, Müslüm Arici","doi":"10.1108/hff-06-2024-0467","DOIUrl":"https://doi.org/10.1108/hff-06-2024-0467","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>This study aims to address the low thermal conductivity and suboptimal performance of phase change materials (PCMs) by examining the impact of geometric adjustments on their melting rate.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>A two-dimensional numerical model was created to investigate the effect of different positions and angular inclinations of the inside heating surface (IHS) on the melting rate of PCM within a latent heat thermal energy storage system. The model analysed the IHS at the centre and below the centre at various positions (10, 20, 30 and 40 mm) and inclinations (0°, 15°, 30°, 45°, 60°, 75° and 90°).</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>The 90° inclination (vertical) significantly reduced the melting time by 75% compared to the 0° inclination (horizontal). The best melting performance was recorded with the IHS positioned 20 mm below the centre. At a 30° inclination, the maximum reduction in melting time was observed with the IHS at 30 and 40 mm placements. The system demonstrated the highest energy storage capacity of 307.72 kJ/kg at a 75° inclination with the IHS positioned 10 mm laterally, and the lowest capacity of 255.02 kJ/kg at a 0° inclination with the IHS at a 30 mm lateral position.</p><!--/ Abstract__block -->\u0000<h3>Practical implications</h3>\u0000<p>To address the deficient part of PCM like low thermal conductivity and below level performance characteristics, a structural (geometrical) adjustment was developed to study the effect on the melting rate of PCM without any cost addition. Using the computational model, an optimised thermal energy storage system is developed that can play a pivotal role in improving the applicability of thermal energy storage systems.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>This research is novel in simultaneously investigating the numerical characteristics of PCM melting behaviour with different lateral positions and angular orientations of the IHS. A unique design modification was introduced, using a 2D numerical model and simulations to explore the effects under isothermal conditions.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"11 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143192137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of temperature jump, first and second-order velocity slip effects on blood-based ternary nanofluid flow in convergent/divergent channels","authors":"Tunahan Gunay, Duygu Erdem, Ahmet Ziyaettin Sahin","doi":"10.1108/hff-10-2024-0772","DOIUrl":"https://doi.org/10.1108/hff-10-2024-0772","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>High surface area-to-volume ratios make nanoparticles ideal for cancer heat therapy and targeted medication delivery. Moreover, ternary nanofluids (TNFs) may possess superior thermophysical properties compared to mono- and hybrid nanofluids due to their synergistic effects. In light of this information, the objective of this article is to examine the blood-based TNF flow within convergent/divergent channels under velocity slip and temperature jump.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>Leading partial differential equations corresponding to the problem are transformed into a system of nonlinear ordinary differential equations by using similarity variables. The bvp4c code that uses the finite difference method is used to obtain a numerical solution.</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>The effect of nanoparticles may change depending on the characteristics of flow near the wall. The properties and proportions of the used nanoparticles become important to control the flow. When TNF was used, an increase in the Nusselt number between 4.75% and 6.10% was observed at low Reynolds numbers. At high Reynolds numbers, nanoparticles reduce the Nusselt number and skin friction coefficient values under some special flow conditions. Importantly, the effects of second-order slip on engineering parameters were also investigated. Furthermore, the Nusselt number increases with increasing shape factor.</p><!--/ Abstract__block -->\u0000<h3>Research limitations/implications</h3>\u0000<p>Obtained results of the study can be beneficial in both nature and engineering, especially blood flow in veins.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>The main innovations of this study are the usage of blood-based TNF and the examination of the effect of shape factor in convergent/divergent channels with second-order velocity slip.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"63 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143077515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Three-dimensional analysis of turbulent twin-swirling jets onto a heated rectangular prism in a channel","authors":"Muhammed Gur, Hakan Oztop, Nirmalendu Biswas, Fatih Selimefendigil","doi":"10.1108/hff-08-2024-0559","DOIUrl":"https://doi.org/10.1108/hff-08-2024-0559","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>The purpose of this study is to investigate the impact of swirling jet flow on the cooling performance of a heated rectangular prism placed within a channel. The primary aim is to explore the influence of varying aspect ratios (AR) of the prism and different fluid Reynolds numbers (Re) on the cooling efficiency.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>The numerical analysis is performed using a finite volume-based solver, which incorporates the large eddy simulations (LES) turbulence model. The setup consists of twin 45° swirling jets directed at isothermally heated bodies, with water used as the cooling medium. The rectangular prism is oriented perpendicularly to the channel flow direction, positioned one unit distance from the inlet. This study examines three distinct aspect ratios (AR = 0.5, 1 and 1.5) and a range of Reynolds numbers (6000 = Re = 20000).</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>The results indicate that cooling efficiency improves as the aspect ratio decreases and the Reynolds number increases. Higher Reynolds numbers enhance jet impingement and turbulent mixing, which are crucial for efficient heat transfer. Conversely, lower Reynolds numbers lead to diminished impingement and reduced cooling efficiency. Increasing the Reynolds number from 6000 to 20000 elevates the average Nusselt number by 35% (for AR = 0.5) and up to 45% (for AR = 1.5). It was observed that lower aspect ratios produce superior cooling effects due to intensified localized jet interactions.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>This research significantly contributes to the fields of fluid dynamics and thermal engineering by elucidating the influence of swirling jet flows on the cooling of heated surfaces. The findings offer valuable insights for optimizing the design and performance of cooling systems across various industrial applications.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"49 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143049905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mixed convection in a partially and differentially heated cavity − a finite volume complete flux analysis","authors":"B. V. Rathish Kumar, Chitranjan Pandey","doi":"10.1108/hff-09-2024-0678","DOIUrl":"https://doi.org/10.1108/hff-09-2024-0678","url":null,"abstract":"&lt;h3&gt;Purpose&lt;/h3&gt;\u0000&lt;p&gt;The purpose of this study is to derive a physics based complete-flux approximation scheme by solving suitable nonlinear boundary value problems (BVP) for finite volume method for mixed convection problems, to study the mixed convection phenomenon inside partially and differentially heated cavity for various sets of flow parameters. And, to study the impact of source terms on the cell-face fluxes for various sets of flow parameters for mixed convection problems.&lt;/p&gt;&lt;!--/ Abstract__block --&gt;\u0000&lt;h3&gt;Design/methodology/approach&lt;/h3&gt;\u0000&lt;p&gt;The governing equations have been discretized by finite volume method on a staggered grid, and the cell-face fluxes have been approximated by local nonlinear BVP. The cell-face flux is represented as a sum of homogeneous and an inhomogeneous flux term. The proposed flux approximation is fully physics based as it considers the pressure gradient term, thermal buoyancy term and the other source terms in the cell-face flux calculation. The scheme comes out to be second order accurate in space tested with known solution. Also, the scheme has been implemented to study the mixed convection problems in a partially and differentially heated cavity.&lt;/p&gt;&lt;!--/ Abstract__block --&gt;\u0000&lt;h3&gt;Findings&lt;/h3&gt;\u0000&lt;p&gt;The numerical order of convergence study shows that the proposed scheme is of second order in space. The scheme is first validated with existing benchmark literature for the mixed convection problem. As the proposed cell-face flux approximation scheme is a homogeneous part and an inhomogeneous part, this study quantifies the influence of the several source terms on the cell-face flux with the help of the inhomogeneous flux term. Then, the mixed convection problems in a partially and differentially heated cavity has been studied. Also, the effect of heat transfer rate at the hot wall is studied for different height of the heat source with different directions of wall movement. The numerical findings show that the local Nusselt number at the left wall is higher when the top and bottom walls move in opposite directions compared to when they move in the same direction, regardless of the Richardson number. In addition, the heat transfer rate at the hot portion of the left wall increases uniformly as the Richardson number decreases when the walls move in opposite directions. However, when the top and bottom walls move in the same direction, the increase in heat transfer rate is not uniform due to the formation of secondary re-circulation of the fluid near the bottom wall.&lt;/p&gt;&lt;!--/ Abstract__block --&gt;\u0000&lt;h3&gt;Originality/value&lt;/h3&gt;\u0000&lt;p&gt;In this work, the flux approximation is conducted through local nonlinear BVPs, an approach that, to the authors’ knowledge, has not been previously applied to mixed convection problems. One of the strong advantages of the proposed scheme is that it can quantify the influence of source terms, namely, pressure gradient, cross-flux and the thermal buoyancy force, on the cell face fluxes required in t","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"38 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143031003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}