Pramana最新文献 - Book学术

Multiphase ferrofluid flow in a rotating system 多相铁磁流体在旋转系统中的流动

IF 1.9 4区物理与天体物理

Pramana Pub Date : 2025-05-19 DOI: 10.1007/s12043-025-02924-5

Anupam Bhandari

{"title":"Multiphase ferrofluid flow in a rotating system","authors":"Anupam Bhandari","doi":"10.1007/s12043-025-02924-5","DOIUrl":"10.1007/s12043-025-02924-5","url":null,"abstract":"<div><p>The current mathematical model investigates the unsteady flow of fluid–particle suspension and multiphase heat exchange in ferrofluid flow over a spinning and upward migrating disk under the constant Kelvin magnetisation force. The motion of the disk along the rotational axis slows its angular velocity, reducing the radial and circumferential motion of the fluid. Excluding the effect of suspended particles, vertical movement of the disk and the Kelvin magnetisation force, the current problem is reduced to the Von Karman rotating disk problem. Normalised nonlinear differential equations of the system are solved using the technique of finite elements. When a magnetic field is present, increasing the volume concentration of ferromagnetic nanoparticles in the flow increases velocity and temperature. The variation in both temperature and velocity of the suspended particles is greater than that of fluid. The magnetic fluid and magnetic particle radial velocities fall by approximately 7% and 6%, respectively, with an increase in the ferromagnetic interaction number (<i>β</i><sub>1</sub>). On the other hand, there was an approximate 4.5% increase in axial velocity. The radial and tangential components of particle velocities, and the particle temperature, are greatly decreased by increasing the vertical motion parameter. The particle's axial velocity does, however, increase.</p></div>","PeriodicalId":743,"journal":{"name":"Pramana","volume":"99 2","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144084987","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Anisotropic compact star: various equations of state 各向异性致密星：各种状态方程

IF 1.9 4区物理与天体物理

Pramana Pub Date : 2025-05-16 DOI: 10.1007/s12043-025-02918-3

Rinkal Patel, B S Ratanpal

引用次数: 0

Impact of appropriate similarity transformations on the heat transfer analysis of the Casson trihybrid shape-dependent nanofluid with suction(/)injection and thermal radiation through a stretching sheet 适当的相似变换对吸力(/)注入和拉伸片热辐射下Casson三杂化纳米流体传热分析的影响

IF 1.9 4区物理与天体物理

Pramana Pub Date : 2025-05-15 DOI: 10.1007/s12043-025-02916-5

B J Gireesha, C G Pavithra

{"title":"Impact of appropriate similarity transformations on the heat transfer analysis of the Casson trihybrid shape-dependent nanofluid with suction(/)injection and thermal radiation through a stretching sheet","authors":"B J Gireesha, C G Pavithra","doi":"10.1007/s12043-025-02916-5","DOIUrl":"10.1007/s12043-025-02916-5","url":null,"abstract":"<div><p>Exploration of a non-linear stretching sheet has been conducted by utilising the Casson model, focussing on an exclusive mixture known as a ternary hybrid nanofluid. This particular nanofluid is a mixture of ethylene glycol hosting suspended graphene, carbon nanotubes and aluminium oxide. The nanoparticles scattered in the underlying liquid are anticipated to exhibit distinct formations like brick blades and lamina, ensuring an efficient connection between the expansive surface of the nanoparticles and the foundational fluid. As a result, this configuration allows for improved absorption of heat from the surface. Many fluid flow problems require the use of a similarity transformation to simplify the equations and make them more tractable. However, it is crucial to derive the correct similarity transformation for each specific problem. Unfortunately, many researchers overlook this step or employ inappropriate transformations, leading to erroneous results. This paper aims to address this issue by systematically deriving suitable similarity transformations for various flow problems, ensuring the accuracy and reliability of the solutions obtained. We derived an appropriate set of similarity transformations for a particular flow problem, in which the similarity variable is dimensionless and appears in the formulation as a function of all independent variables. The numerical solution of the modified equations was obtained using the Runge–Kutta Fehlberg 4–5th method. The study suggests that the temperature distribution is most significant with nanoparticles featuring brick–brick–lamina configurations, followed by brick–brick–blade and brick–brick–brick arrangements.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":743,"journal":{"name":"Pramana","volume":"99 2","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143949528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Influence of magnetic dipole on the hybrid nanofluid flow with chemical reactions due to the generated and absorbed heat 磁偶极子对杂化纳米流体产生和吸收热量的影响

IF 1.9 4区物理与天体物理

Pramana Pub Date : 2025-05-15 DOI: 10.1007/s12043-025-02917-4

R S Varun Kumar, K Chandan, K Venkadeshwaran, Taseer Muhammad, R J Punith Gowda, B C Prasannakumara

{"title":"Influence of magnetic dipole on the hybrid nanofluid flow with chemical reactions due to the generated and absorbed heat","authors":"R S Varun Kumar, K Chandan, K Venkadeshwaran, Taseer Muhammad, R J Punith Gowda, B C Prasannakumara","doi":"10.1007/s12043-025-02917-4","DOIUrl":"10.1007/s12043-025-02917-4","url":null,"abstract":"<div><p>The present study examines the impact of heat source/sink, magnetic dipole and heterogeneous–homogeneous chemical reactions on the hybrid nanofluid flow via a stretching cylinder in the presence of porous media. Scientists and engineers can enhance the efficiency of heat transfer by optimising system flow and investigating the impact of chemical reactions on flow dynamics. Many chemical engineering activities, including absorption, leaching, drying, adsorption, evaporation and solvent extraction, can be used in the analysis of mass transfer to or from surfaces. The governing partial differential equations (PDEs) are modelled and presented. The use of similarity variables transforms the modelled PDEs of the present problem into non-dimensional ordinary differential equations (ODEs). The resultant ordinary differential equations (ODEs) are solved using the Runge–Kutta–Fehlberg fourth–fifth order (RKF-45) method and the obtained results are compared using the physics-informed neural network (PINN) approach. Graphical representations illustrate the effects of various parameters on temperature, concentration and velocity profiles. The thermal profile increases as the ferromagnetic interaction and heat source/sink parameters increase. As homogeneous and heterogeneous reaction parameters rise, the concentration profile decreases. The outcomes obtained by PINN are in good agreement with the solution obtained by RKF-45, indicating good convergence. \u0000</p></div>","PeriodicalId":743,"journal":{"name":"Pramana","volume":"99 2","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143949527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Optical solutions for time-fractional nonlinear Schrödinger equation with Kudryashov’s arbitrary type of generalised nonlinear and refractive index via the new Kudryashov approach 用新的Kudryashov方法求解具有任意广义非线性和折射率的时间分数阶非线性Schrödinger方程

IF 1.9 4区物理与天体物理

Pramana Pub Date : 2025-05-08 DOI: 10.1007/s12043-025-02925-4

Muhammad Amin S Murad, Ahmed H Arnous, Mir Sajjad Hashemi, Mohammad Mirzazadeh

{"title":"Optical solutions for time-fractional nonlinear Schrödinger equation with Kudryashov’s arbitrary type of generalised nonlinear and refractive index via the new Kudryashov approach","authors":"Muhammad Amin S Murad, Ahmed H Arnous, Mir Sajjad Hashemi, Mohammad Mirzazadeh","doi":"10.1007/s12043-025-02925-4","DOIUrl":"10.1007/s12043-025-02925-4","url":null,"abstract":"<div><p>This paper provides a thorough investigation of the new Kudryashov method for obtaining optical solutions relevant to a time-fractional nonlinear Schrödinger equation (NLSE) modified with Kudryashov’s advanced refractive index (RI) formulation. The resulting optical solutions are indicated by their formulation through exponential and hyperbolic functions. To show the significance of these optical solutions, a variety of 2D, 3D and contour visual representations are presented. Additionally, graphical representations are utilised to reveal the dynamic properties of these diverse optical solutions in response to changes in the time parameter and order. The implications of these findings are substantial for their potential application in the propagation of pulses within optical fibres and other areas of physics. Moreover, the model is well-suited for investigating the polarisation of solitons in birefringent fibres. The methodology proposed in this manuscript is suggested to serve as an accurate tool for exploring optical solutions across a range of NLSEs, including both fractional and integer orders. The optical solitons described in this work are expected to have promising applications in the field of nonlinear optics, opening up new avenues for the study and utilisation of soliton dynamics.</p></div>","PeriodicalId":743,"journal":{"name":"Pramana","volume":"99 2","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143925513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Theoretical modelling and nonlinear analysis of galloping flexoelectric energy harvesters with blunt bodies of different sizes 不同尺寸钝体奔驰柔性电能量采集器的理论建模与非线性分析

IF 1.9 4区物理与天体物理

Pramana Pub Date : 2025-04-28 DOI: 10.1007/s12043-025-02893-9

Hanxuan Xu, Ying Luo, Hongguang Liu

{"title":"Theoretical modelling and nonlinear analysis of galloping flexoelectric energy harvesters with blunt bodies of different sizes","authors":"Hanxuan Xu, Ying Luo, Hongguang Liu","doi":"10.1007/s12043-025-02893-9","DOIUrl":"10.1007/s12043-025-02893-9","url":null,"abstract":"<div><p>This study evaluated the behaviour of a novel galloping energy collector based on the flexoelectric effect, for which the dynamic equation governing the energy conversion system is established by applying Hamilton’s principle. The aerodynamic coefficient curve for the blunt body, characterised by width-to-thickness ratios ranging from 1.0 to 2.0, is analysed for various wind angles using the simulation software. The galloping response characteristics of the system and its energy export performance for varying parameters are investigated using numerical simulation. The findings reveal that the number of inflection points in the aerodynamic fitting curves varies across diverse width-to-thickness ratios, resulting in three forms of dynamic responses. This variation significantly impacts energy harvesting. Furthermore, the results demonstrate that for wind speeds (<i>U</i>) from 1 to 3 <span>({text{m}}/{text{s}})</span>, the optimal width-to-thickness ratios for the blunt body fall between 1.5 and 2.0. When <i>U</i> exceeds 3 <span>({text{m}}/{text{s}})</span>, the appropriate width-to-thickness ratio falls within the range of 1.0–1.5. The influence of resistance on the electrical export of the system is also discussed, and the best matching resistance is determined so that the geometrical parameters and the resistance can be designed to realise the optimal regulation of the system’s amplitude, onset wind speed of the galloping dynamic and the electrical export.</p></div>","PeriodicalId":743,"journal":{"name":"Pramana","volume":"99 2","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143879682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Quantum mechanical manifestation of order-chaos-order-chaos-type of switch-over in hydrogen molecule ion perturbed with varying magnetic field 变磁场扰动下氢分子离子有序-混沌-有序-混沌型切换的量子力学表现

IF 1.9 4区物理与天体物理

Pramana Pub Date : 2025-04-28 DOI: 10.1007/s12043-025-02914-7

N Athavan, C Selvaraju

引用次数: 0

Dromion solutions of nonlinear BKK equations using the improved F-expansion method 用改进的f展开法推进非线性BKK方程的解

IF 1.9 4区物理与天体物理

Pramana Pub Date : 2025-04-21 DOI: 10.1007/s12043-025-02915-6

S-F Wang

{"title":"Dromion solutions of nonlinear BKK equations using the improved F-expansion method","authors":"S-F Wang","doi":"10.1007/s12043-025-02915-6","DOIUrl":"10.1007/s12043-025-02915-6","url":null,"abstract":"<div><p>This article investigates a (2 + 1)-dimensional nonlinear Broer–Kaup–Kupershmidt (BKK) equation and proposes an improved F-expansion method for obtaining analytical soliton solutions. We introduce the F-expansion technique, which involves a Riccati equation and hyperbolic functions. Using this approach, various solutions are obtained and some structures are constructed and classified into three categories: dromion solutions, local excitations and self-similar fractal structures. These solutions contribute to understanding the (2 + 1)-dimensional BKK and give vital insights into wave distributions. To obtain the dynamics of the solutions, some results are discussed and some local excitations and self-similar fractal structures (FSs) are presented. For the trial functions are emerged into the dromion solutions, the fractal structures which are self-similar are observed. The physical insight and the dynamics of the dromion solutions describing the wave propagation transmission in optical physics are discussed for different selections of rational polynomial trial functions in the solutions. The significance of this work lies in the successful application of the proposed method to achieve soliton solutions of (2 + 1)-dimensional BKK. Through symbolic calculation, the analytic soliton solutions are extracted, which is beyond the efforts of the previous literature. This method provides a new perspective for studying the BKK equation and its solutions. The results obtained enhance our understanding of the BKK behaviour and pave the way for the next work in this area.</p></div>","PeriodicalId":743,"journal":{"name":"Pramana","volume":"99 2","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143852508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

IF 1.9 4区物理与天体物理

Pramana Pub Date : 2025-04-21 DOI: 10.1007/s12043-025-02909-4

S Dinesh Vijay, K Thamilmaran, A Ishaq Ahamed

引用次数: 0

Quintessence and false vacuum: Two sides of the same coin? 精华与假真空：同一枚硬币的两面？

IF 1.9 4区物理与天体物理

Pramana Pub Date : 2025-04-17 DOI: 10.1007/s12043-025-02910-x

M V Pradosh Keshav, Kenath Arun

{"title":"Quintessence and false vacuum: Two sides of the same coin?","authors":"M V Pradosh Keshav, Kenath Arun","doi":"10.1007/s12043-025-02910-x","DOIUrl":"10.1007/s12043-025-02910-x","url":null,"abstract":"<div><p>We studied the late-time acceleration scenarios using a quintessence field initially trapped in a metastable false vacuum state. The false vacuum has non-zero vacuum energy and can drive exponential expansion if not coupled with gravity. Upon decay of the false vacuum, the quintessence field is released and begins to evolve. We assumed conditions where the effective scalar potential gradient must satisfy <span>(nabla V_{text {eff}} > A)</span>, characterised by a pressure term approximately <span>(Delta p / p > mathcal {O} (hbar ))</span> invoking the string swampland criteria. We then derived the effective potential of the scalar with an upper bound on the coupling constant <span>(lambda < 0.6)</span>. Further analysis revealed that <span>(V_{text {eff}})</span> shows a slow-roll behaviour for <span>(0.1> lambda > -0.04)</span> in the effective dark energy equation of state (EoS) <span>(-0.8< w_0 < -0.4)</span>, stabilising at points between <span>(1< A < 2.718)</span>. Our results suggest a stable scalar decoupled from its initial metastable state can indeed lead to a more stable Universe at later times. However, slight deviations in parameter orders can potentially violate the swampland criteria if <span>(V_{text {eff}})</span> grows too rapidly. Since this is not something we expect, it opens up the possibility that the current dark energy configuration might be a result of a slowly varying scalar potential rather than being arbitrary.</p></div>","PeriodicalId":743,"journal":{"name":"Pramana","volume":"99 2","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143840399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0