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

{"title":"Effect of wing height layout on the aerodynamic performance ofhigh-speed train","authors":"Xiaohui Xiong, Jiaxu Geng, Kaiwen Wang, Xinran Wang","doi":"10.1108/hff-02-2024-0136","DOIUrl":"https://doi.org/10.1108/hff-02-2024-0136","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>This paper aims to investigate the effect of different wing height layouts on the aerodynamic performance and flow structure of high-speed train, in a train-wing coupling method with multiple tandem wings installed on the train roof.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>The improved delayed detached eddy simulation method based on shear stress transport <em>k</em>-<span>\u0000<mml:math display=\"inline\" xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:mtext>ω</mml:mtext></mml:math></span> turbulence model has been used to conduct computational fluid dynamics simulation on the train with three different wing height layouts, at a Reynolds number of 2.8 × 10⁶. The accuracy of the numerical method has been validated by wind tunnel experiments.</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>The wing height layout has a significant effect on the lift, while its influence on the drag is weak. There are three distinctive vortex structures in the flow field: wingtip vortex, train body vortex and pillar vortex, which are influenced by the variation in wing height layout. The incremental wing layout reduces the mixing and merging between vortexes in the flow field, weakening the vorticity and turbulence intensity. This enhances the pressure difference between the upper and lower surfaces of both the train and wings, thereby increasing the overall lift. Simultaneously, it reduces the slipstream velocity at platform and trackside heights.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>This paper contributes to understanding the aerodynamic characteristics and flow structure of a high-speed train coupled with wings. It provides a reference for the design aiming to achieve equivalent weight reduction through aerodynamic lift synergy in trains.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"7 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141973979","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":"Aircraft ice accretion prediction based on geometrical constraints enhancement neural networks","authors":"Wei Suo, Xuxiang Sun, Weiwei Zhang, Xian Yi","doi":"10.1108/hff-01-2024-0019","DOIUrl":"https://doi.org/10.1108/hff-01-2024-0019","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>The purpose of this study is to establish a novel airfoil icing prediction model using deep learning with geometrical constraints, called geometrical constraints enhancement neural networks, to improve the prediction accuracy compared to the non-geometrical constraints model.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>The model is developed with flight velocity, ambient temperature, liquid water content, median volumetric diameter and icing time taken as inputs and icing thickness given as outputs. To enhance the icing prediction accuracy, the model involves geometrical constraints into the loss function. Then the model is trained according to icing samples of 2D NACA0012 airfoil acquired by numerical simulation.</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>The results show that the involvement of geometrical constraints effectively enhances the prediction accuracy of ice shape, by weakening the appearance of fluctuation features. After training, the airfoil icing prediction model can be used for quickly predicting airfoil icing.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>This work involves geometrical constraints in airfoil icing prediction model. The proposed model has reasonable capability in the fast assessment of aircraft icing.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"4 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141899421","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":"Heat transfer characteristics of printed circuit heat exchangers under mechanical vibrations","authors":"Zhengqiang Ding, Li Xu, Yiping Zhang","doi":"10.1108/hff-03-2024-0237","DOIUrl":"https://doi.org/10.1108/hff-03-2024-0237","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>The purpose of this paper is to investigate the impact of mechanical vibration on the heat transfer and pressure drop characteristics of semicircular channel printed circuit heat exchangers (PCHEs), while also establishing correlations between vibration parameters and thermal performance.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>By combining experimental and numerical simulation methods, the heat transfer coefficient and pressure drop characteristics of supercritical carbon dioxide (S-CO₂) in a semicircular channel with a diameter of 2 mm under vibration conditions were studied. Reinforce the research by conducting computational fluid dynamics studies using ANSYS Fluent 22.0, the experimental results were compared with the numerical simulation results to verify the accuracy of the numerical method.</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>The use of vibration has the potential to attenuate the degradation of wall heat transfer caused by buoyancy-induced PCHEs on the upward-facing surface. The heat transfer enhancement (HTE) was maximized by an increase of 18.2%, while the pressure drop enhancement (PDE) was elevated by over 25-fold. The capacity to enhance the heat exchange between S-CO₂ and channel walls through increasing vibration intensity is limited, indicating maximum effectiveness in improving thermal performance.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>Conducting heat transfer experiments on PCHEs with mechanical vibration enhancement and verifying the accuracy of the vibration numerical model. The relation based on the dimensionless factor is derived. To provide theoretical support for using vibration to enhance the heat transfer capability of PCHEs.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"82 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141899423","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":"Study of a combined Kairat-II-X equation: Painlevé integrability, multiple kink, lump and other physical solutions","authors":"Abdul-Majid Wazwaz, Weaam Alhejaili, Samir El-Tantawy","doi":"10.1108/hff-05-2024-0411","DOIUrl":"https://doi.org/10.1108/hff-05-2024-0411","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>This study aims to explore a novel model that integrates the Kairat-II equation and Kairat-X equation (K-XE), denoted as the Kairat-II-X (K-II-X) equation. This model demonstrates the connections between the differential geometry of curves and the concept of equivalence.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>The Painlevé analysis shows that the combined K-II-X equation retains the complete Painlevé integrability.</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>This study explores multiple soliton (solutions in the form of kink solutions with entirely new dispersion relations and phase shifts.</p><!--/ Abstract__block -->\u0000<h3>Research limitations/implications</h3>\u0000<p>Hirota’s bilinear technique is used to provide these novel solutions.</p><!--/ Abstract__block -->\u0000<h3>Practical implications</h3>\u0000<p>This study also provides a diverse range of solutions for the K-II-X equation, including kink, periodic and singular solutions.</p><!--/ Abstract__block -->\u0000<h3>Social implications</h3>\u0000<p>This study provides formal procedures for analyzing recently developed systems that investigate optical communications, plasma physics, oceans and seas, fluid mechanics and the differential geometry of curves, among other topics.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>The study introduces a novel Painlevé integrable model that has been constructed and delivers valuable discoveries.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"49 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141891595","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":"Response surface methodology-based new model to optimize heat transfer and shear stress for ferrites/motor oil hybrid nanofluid","authors":"Sweta, RamReddy Chetteti, Pranitha Janapatla","doi":"10.1108/hff-03-2024-0199","DOIUrl":"https://doi.org/10.1108/hff-03-2024-0199","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>This study aims to optimize heat transfer efficiency and minimize friction factor and entropy generation in hybrid nanofluid flows through porous media. By incorporating factors such as melting effect, buoyancy, viscous dissipation and no-slip velocity on a stretchable surface, the aim is to enhance overall performance. Additionally, sensitivity analysis using response surface methodology is used to evaluate the influence of key parameters on response functions.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>After deriving suitable Lie-group transformations, the modeled equations are solved numerically using the “spectral local linearization method.” This approach is validated through rigorous numerical comparisons and error estimations, demonstrating strong alignment with prior studies.</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>The findings reveal that higher Darcy numbers and melting parameters are associated with decreased entropy (35.86% and 35.93%, respectively) and shear stress, increased heat transmission (16.4% and 30.41%, respectively) in hybrid nanofluids. Moreover, response surface methodology uses key factors, concerning the Nusselt number and shear stress as response variables in a quadratic model. Notably, the model exhibits exceptional accuracy with $R^2$ values of 99.99% for the Nusselt number and 100.00% for skin friction. Additionally, optimization results demonstrate a notable sensitivity to the key parameters.</p><!--/ Abstract__block -->\u0000<h3>Research limitations/implications</h3>\u0000<p>Lubrication is a vital method to minimize friction and wear in the automobile sector, contributing significantly to energy efficiency, environmental conservation and carbon reduction. The incorporation of nickel and manganese zinc ferrites into SAE 20 W-40 motor oil lubricants, as defined by the Society of Automotive Engineers, significantly improves their performance, particularly in terms of tribological attributes.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>This work stands out for its focus on applications such as hybrid electromagnetic fuel cells and nano-magnetic material processing. While these applications are gaining interest, there is still a research gap regarding the effects of melting on heat transfer in a NiZnFe_2O_4-MnZnFe_2O_4/20W40 motor oil hybrid nanofluid over a stretchable surface, necessitating a thorough investigation that includes both numerical simulations and statistical analysis.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"22 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141880367","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":"Physically consistent temperature fields for geophysical inversion based on the parametrized location of an isotherm","authors":"Mariano Tomás Fernandez, Sergio Zlotnik, Pedro Diez","doi":"10.1108/hff-10-2023-0649","DOIUrl":"https://doi.org/10.1108/hff-10-2023-0649","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>This paper aims to provide a method for obtaining physically sound temperature fields to be used in geophysical inversions in the presence of immersed essential conditions.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>The method produces a thermal field in agreement with a given location of the interface between the Lithosphere and Asthenosphere. It leverages the known location of the interface to enforce the location of a given isotherm while relaxing other constraints known with less precision. The method splits the domain: in the Lithosphere the solution is immediately obtained by standard procedures, while in the Asthenosphere a minimization problem is solved to fulfill continuity of temperatures (strongly imposed) and fluxes at the interface (weakly imposed).</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>The numerical methodology, based on the relaxation of the bottom fluxes, correctly recovers the thermal field in the complete domain. To obtain bottom fluxes following geophysical expected values, a constrained minimization strategy is required. The sensitivity of the method could be improved by relaxing other quantities such as lateral fluxes or mantle velocities.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>A statement of the energy balance problem in terms of a known immersed condition is presented. A novel numerical procedure based on a domain-splitting strategy allows the solution of the problem. The procedure is tailored to be used within geophysical inversions and provides physically sound solutions.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"72 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141857637","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":"Velocity slip and temperature jump effects on entropy generation of MHD second-grade hybrid nanofluid in Jeffery-Hamel flow","authors":"Mohamed Kezzar, Nabil Talbi, Saeed Dinarvand, Sanatan Das, Mohamed Rafik Sari, Samia Nasr, Ali Akhlaghi Mozaffar","doi":"10.1108/hff-05-2024-0396","DOIUrl":"https://doi.org/10.1108/hff-05-2024-0396","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>This paper aims to model and analyze Jeffery Hamel’s channel flow with the magnetohydrodynamics second-grade hybrid nanofluid. Considering the importance of studying the velocity slip and temperature jump in the boundary conditions of the flow, which leads to results close to reality, this paper intends to analyze the mentioned topic in the convergent and divergent channels that have significant applications.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>The examination is conducted on a EG-H_2 O &lt;30%–70%&gt; base fluid that contains hybrid nanoparticles (i.e. SWCNT-MWCNT). To ensure comprehensive results, this study also considers the effects of thermal radiation, thermal sink/source, rotating convergent-divergent channels and magnetic fields. Initially, the governing equations are formulated in cylindrical coordinates and then simplified to ordinary differential equations through appropriate transformations. These equations are solved using the Explicit Runge–Kutta numerical method, and the results are compared with previous studies for validation.</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>After the validation, the effect of the governing parameters on the temperature and velocity of the second-grade hybrid nanofluid has been investigated by means of various and comprehensive contours. In the following, the issue of entropy generation and its related graphical results for this problem is presented. The mentioned contours and graphs accurately display the influence of problem parameters, including velocity slip and temperature jump. Besides, when thermal radiation is introduced (Rd = +0.1 and Rd = +0.2), entropy generation in convergent-divergent channels decreases by 7% and 14%, respectively, compared to conditions without thermal radiation (Rd = 0). Conversely, increasing the thermal sink/source from 0 to 4 leads to an 8% increase in entropy generation at Q = 2 and a 17% increase at Q = 4 in both types of channels. The details of the analysis of contours and the entropy generation results are fully mentioned in the body of the paper.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>There are many studies on convergent and divergent channels, but this study comprehensively investigates the effects of velocity slip and temperature jump and certainly, this geometry with the specifications presented in this paper has not been explored before. Among the other distinctive features of this paper compared to previous works, the authors can mention the presentation of velocity and temperature results in the form of contours, which makes the physical analysis of the problem simpler.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"105 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141768453","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 curvature on bubble dynamics and associated heat transfer characteristics for nucleate pool boiling from a hydrophilic curved surface","authors":"Abhishek Kumar Sharma, Shaligram Tiwari","doi":"10.1108/hff-02-2024-0134","DOIUrl":"https://doi.org/10.1108/hff-02-2024-0134","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>This paper aims to carry out numerical study on growth of a single bubble from a curved hydrophilic surface, in nucleate pool boiling (NPB). The boiling performance associated with NPB on a curved surface has been analyzed in contrast to a plane surface.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>Commercial software ANSYS Fluent 2021 R1 has been used with its built-in feature of interface tracking based on volume of fluid method. For water as the working fluid, the effect of microlayer evaporation underneath the bubble base has been included with the help of user-defined function. The phase change behavior at the interface of vapor bubble has been modeled by using “saturated-interface-volume” phase change model.</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>An interesting outcome of the present study is that the bubble departure gets delayed with increase in curvature of the heating surface. Wall heat flux is found to be higher for a curved surface as compared to a plane surface. Effect of wettability on the time for bubble growth is relatively more for the curved surface as compared to that for a plane surface.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>Effect of surface curvature has been investigated on bubble dynamics and also on temporal variation of heat flux. In addition, the impact of surface wettability along with the surface curvature has also been analyzed on bubble morphology and spatial variation of heat flux. Furthermore, the influence of wall superheat on the bubble growth and also the wall heat flux has been studied for fixed angle of contact and varying curvature.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"21 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141768459","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":"Linear stability analysis of micropolar nanofluid flow across the accelerated surface with inclined magnetic field","authors":"U.S. Mahabaleshwar, S.M. Sachin, A.B. Vishalakshi, Gabriella Bognar, Bengt Ake Sunden","doi":"10.1108/hff-05-2024-0372","DOIUrl":"https://doi.org/10.1108/hff-05-2024-0372","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>The purpose of this paper is to study the two-dimensional micropolar fluid flow with conjugate heat transfer and mass transpiration. The considered nanofluid has graphene nanoparticles.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>Governing nonlinear partial differential equations are converted to nonlinear ordinary differential equations by similarity transformation. Then, to analyze the flow, the authors derive the dual solutions to the flow problem. Biot number and radiation effect are included in the energy equation. The momentum equation was solved by using boundary conditions, and the temperature equation solved by using hypergeometric series solutions. Nusselt numbers and skin friction coefficients are calculated as functions of the Reynolds number. Further, the problem is governed by other parameters, namely, the magnetic parameter, radiation parameter, Prandtl number and mass transpiration. Graphene nanofluids have shown promising thermal conductivity enhancements due to the high thermal conductivity of graphene and have a wide range of applications affecting the thermal boundary layer and serve as coolants and thermal management systems in electronics or as heat transfer fluids in various industrial processes.</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>Results show that increasing the magnetic field decreases the momentum and increases thermal radiation. The heat source/sink parameter increases the thermal boundary layer. Increasing the volume fraction decreases the velocity profile and increases the temperature. Increasing the Eringen parameter increases the momentum of the fluid flow. Applications are found in the extrusion of polymer sheets, films and sheets, the manufacturing of plastic wires, the fabrication of fibers and the growth of crystals, among others. Heat sources/sinks are commonly used in electronic devices to transfer the heat generated by high-power semiconductor devices such as power transistors and optoelectronics such as lasers and light-emitting diodes to a fluid medium, thermal radiation on the fluid flow used in spectroscopy to study the properties of materials and also used in thermal imaging to capture and display the infrared radiation emitted by objects.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>Micropolar fluid flow across stretching/shrinking surfaces is examined. Biot number and radiation effects are included in the energy equation. An increase in the volume fraction decreases the momentum boundary layer thickness. Nusselt numbers and skin friction coefficients are presented versus Reynolds numbers. A dual solution is obtained for a shrinking surface.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"58 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141764230","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":"Evidence of stretching/moving sheet-triggered nonlinear similarity flows: atomization and electrospinning with/without air resistance","authors":"Mustafa Turkyilmazoglu","doi":"10.1108/hff-04-2024-0254","DOIUrl":"https://doi.org/10.1108/hff-04-2024-0254","url":null,"abstract":"<h3>Purpose</h3>\u0000<p>The purpose of this study is two-fold. First, it aims to differentiate the response of a stretching jet encountering a quadratic air resistance from the classical jet shape formed in a frictionless medium. Second, it investigates how the resulting jet forms with and without air resistance, seeking evidence that supports the similarity flows frequently studied for stretching/moving thin bodies under the boundary layer approximation.</p><!--/ Abstract__block -->\u0000<h3>Design/methodology/approach</h3>\u0000<p>This study extends the established electrohydrodynamic stretching jet theory, used to model electrospinning or jet printing in the absence of air resistance, to encompass the impact of the retarding force on the jet stretching in both the cone and final regimes before it impinges on a substrate.</p><!--/ Abstract__block -->\u0000<h3>Findings</h3>\u0000<p>A close examination of the nonlinear governing equations reveals that the jet rapidly thins near the nozzle because of the combined action of viscous and electrical forces. In this region, the exponentially decaying jet receives further support from the air resistance, resulting in a closer alignment with the observed experimental jet. This exponential decay, accelerated by the inversely quadratic speed of the liquid particles, serves as clear evidence for the existence of a similarity flow over an exponentially stretching sheet. Furthermore, in the final regime, the jet stretching exhibits an algebraic decay in the absence of air friction, while with air resistance, it decays exponentially to reach a limiting speed. In the former case, a square root dependence of the stretching jet speed leads to the emergence of a similarity flow over a thin stretching jet, while in the latter case, a Sakiadis’ similarity flow appears over a continuously moving flat surface.</p><!--/ Abstract__block -->\u0000<h3>Practical implications</h3>\u0000<p>The analysis goes beyond jet hydrodynamics, delving into the interplay of electrostatic forces (including Coulomb’s law) and quadratic air drag, drawing upon experimental data on glycerol liquid presented in earlier publications.</p><!--/ Abstract__block -->\u0000<h3>Originality/value</h3>\u0000<p>Finally, the asymptotic behavior of the stretching jet under the combined influence of electrostatic pull and its electric currents because of bulk conduction and surface convection is validated through a comprehensive numerical simulation of the nonlinear system.</p><!--/ Abstract__block -->","PeriodicalId":14263,"journal":{"name":"International Journal of Numerical Methods for Heat & Fluid Flow","volume":"211 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141764231","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}