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

{"title":"Plane dilatational and shear waves in a chiral porous thermoelastic medium under strain gradient theory","authors":"Aakash Kumar, Suraj Goyal","doi":"10.1108/hff-06-2024-0453","DOIUrl":"https://doi.org/10.1108/hff-06-2024-0453","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>This study aims to investigate time-harmonic wave propagation in a chiral porous thermoelastic solid under strain gradient theory (SGT), focusing on identifying and characterizing distinct wave modes within the medium.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>Using Iesan's gradient theory, which incorporates chiral effects and accommodates second sound phenomena, the authors derive mathematical formulations for the velocities and attenuations of eight propagating waves: four dilatational waves and two pairs of coupled shear waves (one left circularly polarized, the other right). Numerical simulations are performed for a specific model, exploring the influence of various parameters on wave propagation.</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>The authors establish that the medium supports four dilatational waves, including a microstretch-associated wave, and four shear waves, distinguished by their chiral-induced characteristics. The results highlight the frequency-dependent dispersive nature of all propagating waves and establish connections with existing theoretical frameworks, demonstrating the broader applicability of our findings.</p><!--/ Abstract__block -->\u0000<h3>Practical implications</h3>\u0000<p>The characteristics of wave propagation in chiral media examined here can enhance our understanding of chiral medium behavior. This knowledge is crucial for developing materials with pronounced chiral effects, surpassing those found in natural chiral materials like bone, quartz, sugar and wood. Advances in artificial chiral materials are driven by their superior toughness, durability and other beneficial properties. Consequently, this study has potential applications across various fields, including the design of chiral broadband absorbers and filters, the production of artificial bones and medical devices, aeronautical engineering and beyond.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>This research extends existing theories and deepens the understanding by exploring wave behaviors in chiral media, advancing this emerging field.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"192 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142397662","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":"Dual characteristics of mixed convection flow of three-particle aqueous nanofluid upon a shrinking porous plate","authors":"Nepal Chandra Roy, Md. Mahmudul Hassan, Saeed Dinarvand","doi":"10.1108/hff-08-2024-0584","DOIUrl":"https://doi.org/10.1108/hff-08-2024-0584","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>This study aims to analyze the thermo-hydrodynamic characteristics for the mixed convection boundary layer flow of three-particle aqueous nanofluid on a shrinking porous plate with the influences of thermal radiation and magnetic field.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>The basic equations have been normalized with the help of similarity transformations. The obtained equations have been solved numerically using the shooting method in conjunction with the sixth-order Runge–Kutta technique. Numerical results for the velocity and temperature are illustrated with varying relevant parameters.</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>The results reveal that the local drag coefficient increases with higher values of the magnetic field parameter, nanoparticle volume fraction and suction parameter. On the other hand, boosting the radiation parameter and nanoparticle concentration notably enhances heat transfer. Furthermore, it is noted that the suction parameter and magnetic field parameter both lead to an increase in velocity and promote the occurrence of dual solutions within the problem conditions.</p><!--/ Abstract__block -->\u0000<h3>Research limitations/implications</h3>\u0000<p>The limitations are that the model is appropriate for thermal equilibrium of base fluid and nanoparticles, and constant thermo-physical properties.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>To the best of the authors' knowledge, no study has taken an attempt to predict the flow and heat transfer characteristics of unsteady mixed convection ternary hybrid nanofluid flow over a shrinking sheet, particularly under the influence of magnetic field and radiation. The findings obtained here may hold particular significance for those interested in the underlying theoretical and practical implications.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"54 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142385239","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":"Analysis of efficient discretization technique for nonlinear integral equations of Hammerstein type","authors":"Imtiyaz Ahmad Bhat, Lakshmi Narayan Mishra, Vishnu Narayan Mishra, Cemil Tunc","doi":"10.1108/hff-06-2024-0459","DOIUrl":"https://doi.org/10.1108/hff-06-2024-0459","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>This study focuses on investigating the numerical solution of second-kind nonlinear Volterra–Fredholm–Hammerstein integral equations (NVFHIEs) by discretization technique. The purpose of this paper is to develop an efficient and accurate method for solving NVFHIEs, which are crucial for modeling systems with memory and cumulative effects, integrating past and present influences with nonlinear interactions. They are widely applied in control theory, population dynamics and physics. These equations are essential for solving complex real-world problems.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>Demonstrating the solution’s existence and uniqueness in the equation is accomplished by using the Picard iterative method as a key technique. Using the trapezoidal discretization method is the chosen approach for numerically approximating the solution, yielding a nonlinear system of algebraic equations. The trapezoidal method (TM) exhibits quadratic convergence to the solution, supported by the application of a discrete Grönwall inequality. A novel Grönwall inequality is introduced to demonstrate the convergence of the considered method. This approach enables a detailed analysis of the equation’s behavior and facilitates the development of a robust solution method.</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>The numerical results conclusively show that the proposed method is highly efficacious in solving NVFHIEs, significantly reducing computational effort. Numerical examples and comparisons underscore the method’s practicality, effectiveness and reliability, confirming its outstanding performance compared to the referenced method.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>Unlike existing approaches that rely on a combination of methods to tackle different aspects of the complex problems, especially nonlinear integral equations, the current approach presents a significant single-method solution, providing a comprehensive approach to solving the entire problem. Furthermore, the present work introduces the first numerical approaches for the considered integral equation, which has not been previously explored in the existing literature. To the best of the authors’ knowledge, the work is the first to address this equation, providing a foundational contribution for future research and applications. This innovative strategy not only simplifies the computational process but also offers a more comprehensive understanding of the problem’s dynamics.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"22 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142325355","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":"Radiative influence on axisymmetric ternary hybrid nanofluid flow with convective boundary conditions over a nonlinearly permeable stretching/shrinking disk","authors":"Farah Nadzirah Jamrus, Anuar Ishak, Iskandar Waini, Umair Khan","doi":"10.1108/hff-04-2024-0324","DOIUrl":"https://doi.org/10.1108/hff-04-2024-0324","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>In recent times, ternary hybrid nanofluid has garnered attention from scientist and researchers due to its improved thermal efficiency. This study aims to delve into the examination of ternary hybrid nanofluid (Al₂O₃–Cu–TiO₂/water), particularly concerning axisymmetric flow over a nonlinearly permeable stretching/shrinking disk. In addition, the investigation of convective boundary conditions and thermal radiation effects is also considered within the context of the described flow problem.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>Mathematical formulations representing this problem are reduced into a set of ordinary differential equations (ODEs) using similarity transformation. The MATLAB boundary value problem solver is then used to solve the obtained set of ODEs. The impact of considered physical parameters such as suction parameter, radiation parameter, nonlinear parameter, nanoparticle volumetric concentration and Biot number on the flow profiles as well as the physical quantities is illustrated in graphical form.</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>The findings revealed the thermal flux for the nonlinearly shrinking disk is approximately 1.33%, significantly higher when compared to the linearly shrinking disk. Moreover, the existence of dual solutions attributed to the nonlinear stretching/shrinking disk is unveiled, with the first solution being identified as the stable and reliable solution through temporal stability analysis.</p><!--/ Abstract__block -->\u0000<h3>Practical implications</h3>\u0000<p>Understanding ternary hybrid nanofluid behavior and flow has applications in engineering, energy systems and materials research. This study may help develop and optimize nanofluid systems like heat exchangers and cooling systems.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>The study of flow dynamics across nonlinear stretching/shrinking disk gains less attention compared to linear stretching/shrinking geometries. Many natural and industrial processes involve nonlinear changes in boundary shapes or sizes. Understanding flow dynamics over nonlinear shrinking/stretching disks is therefore essential for applications in various fields such as materials processing, biomedical engineering and environmental sciences. Hence, this study highlights the axisymmetric flow over a nonlinear stretching/shrinking disk using ternary hybrid nanofluid composed of alumina (Al₂O₃), copper (Cu) and titania (TiO₂). Besides, this study tackles a complex problem involving multiple factors such as suction, radiation and convective boundary conditions. Analyzing such complex systems can provide valuable insights into real-world phenomena where multiple factors interact.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"25 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142325352","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":"Casson-Williamson ternary hybrid nanofluid flow over a yawed cylinder with the impacts of multiple slips","authors":"Prabhugouda Mallanagouda Patil, Bharath Goudar, Ebrahim Momoniat","doi":"10.1108/hff-03-2024-0176","DOIUrl":"https://doi.org/10.1108/hff-03-2024-0176","url":null,"abstract":"&lt;h3&gt;Purpose&lt;/h3&gt;\u0000&lt;p&gt;Many industries use non-Newtonian ternary hybrid nanofluids (THNF) because of how well they control rheological and heat transport. This being the case, this paper aims to numerically study the Casson-Williamson THNF flow over a yawed cylinder, considering the effects of several slips and an inclined magnetic field. The THNF comprises Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;-TiO&lt;sub&gt;2&lt;/sub&gt;-SiO&lt;sub&gt;2&lt;/sub&gt; nanoparticles because they improve heat transmission due to large thermal conductivity.&lt;/p&gt;&lt;!--/ Abstract__block --&gt;\u0000&lt;h3&gt;Design/methodology/approach&lt;/h3&gt;\u0000&lt;p&gt;Applying suitable nonsimilarity variables transforms the coupled highly dimensional nonlinear partial differential equations (PDEs) into a system of nondimensional PDEs. To accomplish the goal of achieving the solution, an implicit finite difference approach is used in conjunction with Quasilinearization. With the assistance of a script written in MATLAB, the numerical results and the graphical representation of those solutions were ascertained.&lt;/p&gt;&lt;!--/ Abstract__block --&gt;\u0000&lt;h3&gt;Findings&lt;/h3&gt;\u0000&lt;p&gt;As the Casson parameter &lt;span&gt;\u0000&lt;mml:math display=\"inline\" xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;mml:mi&gt;β&lt;/mml:mi&gt;&lt;/mml:math&gt;&lt;/span&gt; increases, there is an improvement in the velocity profiles in both chord and span orientations, while the gradients &lt;span&gt;\u0000&lt;mml:math display=\"inline\" xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;mml:mrow&gt;&lt;mml:mi&gt;R&lt;/mml:mi&gt;&lt;mml:msup&gt;&lt;mml:mi&gt;e&lt;/mml:mi&gt;&lt;mml:mrow&gt;&lt;mml:mn&gt;1&lt;/mml:mn&gt;&lt;mml:mo&gt;/&lt;/mml:mo&gt;&lt;mml:mn&gt;2&lt;/mml:mn&gt;&lt;/mml:mrow&gt;&lt;/mml:msup&gt;&lt;mml:msub&gt;&lt;mml:mi&gt;C&lt;/mml:mi&gt;&lt;mml:mi&gt;f&lt;/mml:mi&gt;&lt;/mml:msub&gt;&lt;mml:mo&gt;,&lt;/mml:mo&gt;&lt;mml:mtext&gt; &lt;/mml:mtext&gt;&lt;mml:mi&gt;R&lt;/mml:mi&gt;&lt;mml:msup&gt;&lt;mml:mi&gt;e&lt;/mml:mi&gt;&lt;mml:mrow&gt;&lt;mml:mn&gt;1&lt;/mml:mn&gt;&lt;mml:mo&gt;/&lt;/mml:mo&gt;&lt;mml:mn&gt;2&lt;/mml:mn&gt;&lt;/mml:mrow&gt;&lt;/mml:msup&gt;&lt;mml:msub&gt;&lt;mml:mover accent=\"true\"&gt;&lt;mml:mi&gt;C&lt;/mml:mi&gt;&lt;mml:mo&gt;¯&lt;/mml:mo&gt;&lt;/mml:mover&gt;&lt;mml:mi&gt;f&lt;/mml:mi&gt;&lt;/mml:msub&gt;&lt;/mml:mrow&gt;&lt;/mml:math&gt;&lt;/span&gt; reduce for the same variations of &lt;span&gt;\u0000&lt;mml:math display=\"inline\" xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;mml:mi&gt;β&lt;/mml:mi&gt;&lt;/mml:math&gt;&lt;/span&gt;. The velocities of Casson THNF are greater than those of Casson-Williamson THNF. Approximately, a 202% and a 32% ascension are remarked in the magnitudes of &lt;span&gt;\u0000&lt;mml:math display=\"inline\" xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;mml:mrow&gt;&lt;mml:mi&gt;R&lt;/mml:mi&gt;&lt;mml:msup&gt;&lt;mml:mi&gt;e&lt;/mml:mi&gt;&lt;mml:mrow&gt;&lt;mml:mn&gt;1&lt;/mml:mn&gt;&lt;mml:mo&gt;/&lt;/mml:mo&gt;&lt;mml:mn&gt;2&lt;/mml:mn&gt;&lt;/mml:mrow&gt;&lt;/mml:msup&gt;&lt;mml:msub&gt;&lt;mml:mi&gt;C&lt;/mml:mi&gt;&lt;mml:mi&gt;f&lt;/mml:mi&gt;&lt;/mml:msub&gt;&lt;/mml:mrow&gt;&lt;/mml:math&gt;&lt;/span&gt; and &lt;span&gt;\u0000&lt;mml:math display=\"inline\" xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"&gt;&lt;mml:mrow&gt;&lt;mml:mi&gt;R&lt;/mml:mi&gt;&lt;mml:msup&gt;&lt;mml:mi&gt;e&lt;/mml:mi&gt;&lt;mml:mrow&gt;&lt;mml:mn&gt;1&lt;/mml:mn&gt;&lt;mml:mo&gt;/&lt;/mml:mo&gt;&lt;mml:mn&gt;2&lt;/mml:mn&gt;&lt;/mml:mrow&gt;&lt;/mml:msup&gt;&lt;mml:msub&gt;&lt;mml:mover accent=\"true\"&gt;&lt;mml:mi&gt;C&lt;/mml:mi&gt;&lt;mml:mo&gt;¯&lt;/mml:mo&gt;&lt;/mml:mover&gt;&lt;mml:mi&gt;f&lt;/mml:mi&gt;&lt;/mml:msub&gt;&lt;/mml:mrow&gt;&lt;/mml:math&gt;&lt;/span&gt; for Casson-Williamson THNF than the Casson THNF only. When velocity slip attribute ","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"13 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142276056","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":"Thermally radiative nanofluid heat transfer analysis inside a closed chamber with gyrotactic microorganisms","authors":"Paluru Sreedevi, P. Sudarsana Reddy","doi":"10.1108/hff-02-2024-0146","DOIUrl":"https://doi.org/10.1108/hff-02-2024-0146","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>This paper aims to numerically examine the impact of gyrotactic microorganisms and radiation on heat transport features of magnetic nanoliquid within a closed cavity. Thermophoresis, chemical reaction and Brownian motion are also considered in flow geometry for the moment of nanoparticles.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>Finite element method (FEM) was depleted to numerically approximate the temperature, momentum, concentration and microorganisms concentration of the nanoliquid. The present simulation was unsteady state, and the resulting transformed equations are simulated by FEM-based Mathematica algorithm.</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>It has been found that isotherm patterns get larger with increasing values of the magnetic field parameter. Additionally, numerical codes for rate of heat transport impedance inside the cavity with an increasing Brownian motion parameter values.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>To the best of the authors’ knowledge, the research work carried out in this paper is new, and no part is copied from others’ works.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"37 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142276073","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":"Computational study on cilia transport of Prandtl nanofluid (blood-Fe3O4) enhancing convective heat transfer along microorganisms under electroosmotic effects in wavy capillaries","authors":"Madiha Ajmal, Rashid Mehmood, Noreen Sher Akbar, Taseer Muhammad","doi":"10.1108/hff-07-2024-0503","DOIUrl":"https://doi.org/10.1108/hff-07-2024-0503","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>This study aims to focuse on the flow behavior of a specific nanofluid composed of blood-based iron oxide nanoparticles, combined with motile gyrotactic microorganisms, in a ciliated channel with electroosmosis.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>This study applies a powerful mathematical model to examine the combined impacts of bio convection and electrokinetic forces on nanofluid flow. The presence of cilia, which are described as wave-like motions on the channel walls, promotes fluid propulsion, which improves mixing and mass transport. The velocity and dispersion of nanoparticles and microbes are modified by the inclusion of electroosmosis, which is stimulated by an applied electric field. This adds a significant level of complexity.</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>To ascertain their impact on flow characteristics, important factors such as bio convection Rayleigh number, Grashoff number, Peclet number and Lewis number are varied. The results demonstrate that while the gyrotactic activity of microorganisms contributes to the stability and homogeneity of the nanofluid distribution, electroosmotic forces significantly enhance fluid mixing and nanoparticle dispersion. This thorough study clarifies how to take advantage of electroosmosis and bio convection in ciliated micro channels to optimize nanofluid-based biomedical applications, such as targeted drug administration and improved diagnostic processes.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>First paper discussed “Numerical Computation of Cilia Transport of Prandtl Nanofluid (Blood-Fe₃O₄) Enhancing Convective Heat Transfer along Micro Organisms under Electroosmotic effects in Wavy Capillaries”.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"243 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142234508","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":"Monotonic unbounded schemes transformer (MUST): an approach to remove undershoots and overshoots in family of unbounded schemes using finite-volume method","authors":"Y.F. Yap, J.C. Chai","doi":"10.1108/hff-04-2024-0293","DOIUrl":"https://doi.org/10.1108/hff-04-2024-0293","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>This paper presents a Monotonic Unbounded Schemes Transformer (MUST) approach to bound/monotonize (remove undershoots and overshoots) unbounded spatial differencing schemes automatically, and naturally. Automatically means the approach (1) captures the critical cell Peclet number when an unbounded scheme starts to produce physically unrealistic solution automatically, and (2) removes the undershoots and overshoots as part of the formulation without requiring human interventions. Naturally implies, all the terms in the discretization equation of the unbounded spatial differencing scheme are retained.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>The authors do not formulate new higher-order scheme. MUST transforms an unbounded higher-order scheme into a bounded higher-order scheme.</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>The solutions obtained with MUST are identical to those without MUST when the cell Peclet number is smaller than the critical cell Peclet number. For cell Peclet numbers larger than the critical cell Peclet numbers, MUST sets the nodal values to the limiter value which can be derived for the problem at-hand. The authors propose a way to derive the limiter value. The authors tested MUST on the central differencing scheme, the second-order upwind differencing scheme and the QUICK differencing scheme. In all cases tested, MUST is able to (1) capture the critical cell Peclet numbers; the exact locations when overshoots and undershoots occur, and (2) limit the nodal value to the value of the limiter values. These are achieved by retaining all the discretization terms of the respective differencing schemes naturally and accomplished automatically as part of the discretization process. The authors demonstrated MUST using one-dimensional problems. Results for a two-dimensional convection–diffusion problem are shown in Appendix to show generality of MUST.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>The authors present an original approach to convert any unbounded scheme to bounded scheme while retaining all the terms in the original discretization equation.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"14 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142234471","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 double diffusion natural convection of power-law Non-Newtonian Nano-Encapsulated phase change materials in a trapezoidal enclosure","authors":"Khairunnahar Suchana, Md. Mamun Molla","doi":"10.1108/hff-02-2024-0170","DOIUrl":"https://doi.org/10.1108/hff-02-2024-0170","url":null,"abstract":"&lt;h3&gt;Purpose&lt;/h3&gt;\u0000&lt;p&gt;The present numerical investigation examines the magnetohydrodynamic (MHD) double diffusion natural convection of power-law non-Newtonian nano-encapsulated phase change materials (NEPCMs) in a trapezoidal cavity.&lt;/p&gt;&lt;!--/ Abstract__block --&gt;\u0000&lt;h3&gt;Design/methodology/approach&lt;/h3&gt;\u0000&lt;p&gt;The governing Navier-Stokes, energy and concentration equations based on the Cartesian curvilinear coordinates are solved using the collocated grid arrangement’s finite volume method. The in-house FORTRAN code is validated with the different benchmark problems. The NEPCM nanoparticles consist of a core-shell structure with Phase Change Material (PCM) at the core. The enclosure, shaped as a trapezoidal hollow, features a warmed (&lt;em&gt;T&lt;sub&gt;h&lt;/sub&gt;&lt;/em&gt;) left wall and a cold (&lt;em&gt;T&lt;sub&gt;c&lt;/sub&gt;&lt;/em&gt;) right wall. Various parameters are considered, including the power law index (0.6 ≤ &lt;em&gt;n&lt;/em&gt; ≤ 1.4), Hartmann number (0 ≤ &lt;em&gt;Ha&lt;/em&gt; ≤ 30), Rayleigh number (10&lt;sup&gt;4&lt;/sup&gt; ≤ &lt;em&gt;Ra&lt;/em&gt; ≤ 10&lt;sup&gt;5&lt;/sup&gt;) and fixed variables such as buoyancy ratio (&lt;em&gt;Br&lt;/em&gt; = 0.8), Prandtl number (&lt;em&gt;Pr&lt;/em&gt; = 6.2), Lewis number (&lt;em&gt;Le&lt;/em&gt; = 5), fusion temperature (Θ&lt;sub&gt;&lt;em&gt;f&lt;/em&gt;&lt;/sub&gt; = 0.5) and volume fraction (ϕ = 0.04).&lt;/p&gt;&lt;!--/ Abstract__block --&gt;\u0000&lt;h3&gt;Findings&lt;/h3&gt;\u0000&lt;p&gt;The findings indicate a decrease in local Nusselt (&lt;em&gt;Nu&lt;/em&gt;) and Sherwood (&lt;em&gt;Sh&lt;/em&gt;) numbers with increasing Hartmann numbers (&lt;em&gt;Ha&lt;/em&gt;). Additionally, for a shear-thinning fluid (&lt;em&gt;n&lt;/em&gt; = 0.6) results in the maximum local &lt;em&gt;Nu&lt;/em&gt; and &lt;em&gt;Sh&lt;/em&gt; values. As the Rayleigh number (&lt;em&gt;Ra&lt;/em&gt;) increases from 10&lt;sup&gt;4&lt;/sup&gt; to 10&lt;sup&gt;5&lt;/sup&gt;, the structured vortex in the streamline pattern is disturbed. Furthermore, for different &lt;em&gt;Ra&lt;/em&gt; values, an increase in &lt;em&gt;n&lt;/em&gt; from 0.6 to 1.4 leads to a 67.43% to 76.88% decrease in average &lt;em&gt;Nu&lt;/em&gt; and a 70% to 77% decrease in average &lt;em&gt;Sh&lt;/em&gt;.&lt;/p&gt;&lt;!--/ Abstract__block --&gt;\u0000&lt;h3&gt;Research limitations/implications&lt;/h3&gt;\u0000&lt;p&gt;This research is for two-dimensioal laminar flow only.&lt;/p&gt;&lt;!--/ Abstract__block --&gt;\u0000&lt;h3&gt;Practical implications&lt;/h3&gt;\u0000&lt;p&gt;PCMs represent a class of practical substances that behave as a function of temperature and have the innate ability to absorb, release and store heated energy in the form of hidden fusion enthalpy, or heat. They are valuable in these systems as they can store significant energy at a relatively constant temperature through their latent heat phase change.&lt;/p&gt;&lt;!--/ Abstract__block --&gt;\u0000&lt;h3&gt;Originality/value&lt;/h3&gt;\u0000&lt;p&gt;As per the literature review and the authors’ understanding, an examination has never been conducted on MHD double diffusion natural convection of power-law non-Newtonian NEPCMs within a trapezoidal enclosure. The current work is innovative since it combines NEPCMs with the effect of magnetic field Double diffusion Natural Convection of power-law non-Newtonian NEPCMs in a Trapezoidal enclosure. This outcome can be used to improve thermal management in energy storage systems, increasing safety","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"52 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142170867","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":"Bright and dark optical solitons in optical metamaterials using a variety of distinct schemes for a generalized Schrodinger equation","authors":"Suheil Khuri, Abdul-Majid Wazwaz","doi":"10.1108/hff-05-2024-0408","DOIUrl":"https://doi.org/10.1108/hff-05-2024-0408","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>The purpose of this study is to investigate the nonlinear Schrödinger equation (NLS) incorporating spatiotemporal dispersion and other dispersive effects. The goal is to derive various soliton solutions, including bright, dark, singular, periodic and exponential solitons, to enhance the understanding of soliton propagation dynamics in nonlinear metamaterials (MMs) and contribute new findings to the field of nonlinear optics.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>The research uses a range of powerful mathematical approaches to solve the NLS. The proposed methodologies are applied systematically to derive a variety of optical soliton solutions, each demonstrating unique optical behaviors and characteristics. The approach ensures that both the theoretical framework and practical implications of the solutions are thoroughly explored.</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>The study successfully derives several types of soliton solutions using the aforementioned mathematical approaches. Key findings include bright optical envelope solitons, dark optical envelope solitons, periodic solutions, singular solutions and exponential solutions. These results offer new insights into the behavior of ultrashort solitons in nonlinear MMs, potentially aiding further research and applications in nonlinear wave studies.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>This study makes an original contribution to nonlinear optics by deriving new soliton solutions for the NLS with spatiotemporal dispersion. The diversity of solutions, including bright, dark, periodic, singular and exponential solitons, adds substantial value to the existing body of knowledge. The use of distinct and reliable methodologies to obtain these solutions underscores the novelty and potential applications of the research in advancing optical technologies. The originality lies in the novel approaches used to obtain these diverse soliton solutions and their potential impact on the study and application of nonlinear waves in MMs.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"6 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142166245","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}