Theoretical and Mathematical Physics最新文献_第5页

Thermal behavior study of carbon nanofiber nanofluids and banana leaf nanofluids in a rotating disk flow 碳纳米纤维纳米流体和香蕉叶纳米流体在旋转圆盘流中的热行为研究

IF 1.1 4区物理与天体物理

Theoretical and Mathematical Physics Pub Date : 2025-06-25 DOI: 10.1134/S0040577925060054

K. Jyothi, A. P. Lingaswamy

引用次数: 0

Magnetohydrodynamic flow through a porous medium in a coaxial circular duct 在同轴圆形管道中通过多孔介质的磁流体动力学流动

IF 1.1 4区物理与天体物理

Theoretical and Mathematical Physics Pub Date : 2025-06-25 DOI: 10.1134/S0040577925060091

M. Siva Sankar Reddy, E. Kiran Babu, K. Raghavendra

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Effects of aligned magnetic field and thermal radiation on an unsteady MHD Jeffrey nanofluid flow past an isothermal inclined plate 对准磁场和热辐射对非定常MHD杰弗里纳米流体流过等温倾斜板的影响

IF 1.1 4区物理与天体物理

Theoretical and Mathematical Physics Pub Date : 2025-06-25 DOI: 10.1134/S0040577925060145

A. P. Lingaswamy, Annareddy Sailakumari, Palle Prathapa Reddy, Damodara Reddy Annapureddy, A. G. Gopinath

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Effects of thermo physical aspects of radiant-heating on an unsteady magnetohydrodynamic hybrid nanofluid flow 辐射加热对非定常磁流体动力混合纳米流体流动的热物理影响

IF 1.1 4区物理与天体物理

Theoretical and Mathematical Physics Pub Date : 2025-06-25 DOI: 10.1134/S0040577925060182

K. Viswanath, A. P. Lingaswamy, K. Raghavendra, Raghunath Kodi, Ramachandra Reddy Vaddemani

{"title":"Effects of thermo physical aspects of radiant-heating on an unsteady magnetohydrodynamic hybrid nanofluid flow","authors":"K. Viswanath, A. P. Lingaswamy, K. Raghavendra, Raghunath Kodi, Ramachandra Reddy Vaddemani","doi":"10.1134/S0040577925060182","DOIUrl":"10.1134/S0040577925060182","url":null,"abstract":" We investigate an unsteady magnetohydrodynamic temperature and mass transfer of a hybrid tiny fluid mixed convection transfer of fluids through permeable material over a stretching sheet. The influence of thermal radiation and activation energy is also taken into consideration. In order to create hybrid nanoparticles, nanoparticles of titanium oxide (TiO(_2)) and nanoparticles of alumina (Al(_2)O(_3)) are mixed, and the base fluid is used as water. The set of discrete differential equations with nonlinear behavior that govern the fluid flow is transformed into a set of ordinary differential equations by the use of a similarity transformation and nondimensional variables. These equations are solved numerically by employing the Runge–Kutta fourth-order method in conjunction with various firing techniques. The consequences of a large number of interconnected factors, such as the magnetic field factors, the Prandtl number, the buoyancy factors, the unsteady factors, thermal radiation, the rate of chemical reaction, and the energy of activation are plotted and analyzed in relation to the velocity, temperature, and concentration profiles. The study reveals that increasing the magnetic field reduces fluid velocity, while higher activation energy and chemical reaction rates decrease concentration. Thermal radiation enhances temperature profiles, and the Prandtl number inversely affects the temperature. ","PeriodicalId":797,"journal":{"name":"Theoretical and Mathematical Physics","volume":"223 3","pages":"1087 - 1102"},"PeriodicalIF":1.1,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145144973","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

Drug concentration after intravenous administration: A mathematical approach 静脉给药后药物浓度：一种数学方法

IF 1.1 4区物理与天体物理

Theoretical and Mathematical Physics Pub Date : 2025-06-25 DOI: 10.1134/S0040577925060066

K. Lakshmi Narayan, K. Kondala Rao, V. Sivaramakrishna Reddy, G. Ranjith Kumar, K. Ramesh

引用次数: 0

A study on the expansion of the universe with Lyra geometry in a Bianchi type V space–time in the presence of dark energy 在比安奇V型时空中暗能量存在下的天琴座几何宇宙膨胀研究

IF 1.1 4区物理与天体物理

Theoretical and Mathematical Physics Pub Date : 2025-06-25 DOI: 10.1134/S0040577925060029

D. I. Mazumder

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Hybrid FEM-neural network approach to radiative slip flow of TiO(_2)–SiO(_2) nanofluid over stretching surfaces 混合fem -神经网络方法研究TiO (_2) -SiO (_2)纳米流体在拉伸表面上的辐射滑移流动

IF 1.1 4区物理与天体物理

Theoretical and Mathematical Physics Pub Date : 2025-06-25 DOI: 10.1134/S0040577925060133

K. Jyothi, A. P. Lingaswamy

{"title":"Hybrid FEM-neural network approach to radiative slip flow of TiO(_2)–SiO(_2) nanofluid over stretching surfaces","authors":"K. Jyothi, A. P. Lingaswamy","doi":"10.1134/S0040577925060133","DOIUrl":"10.1134/S0040577925060133","url":null,"abstract":" We study the thermal performance and chemical reactive flow of a hybrid nanofluid over a stretching sheet heat generation. Titanium oxide (TiO(_{2})) and silicon dioxide (SiO(_{2})) combine to form a hybrid nanofluid, which is an improper fluid with water, Eg((50,{:},50)) as a general fluid. Using a suitable similarity variable, the constitutive partial differential equations are converted into a system of connected nonlinear ordinary differential equations. The resulting equations are then solved numerically using the efficient finite element analysis method with the help of Mathematica 10.4 software and, for better results, with the Neural Network Levenberg–Marquardt method in MATLAB R2017b. The present study can be useful in precision engineering and nanotechnology tasks such as developing microfluidic devices and biomedical apparatuses where nanofluid flow control is crucial. The model assists in understanding fluid dynamics for complex cooling systems, particularly in industries where efficient heat transfer is essential, such as electronics and aerospace. Surface tension plays a major role in determining the uniformity and quality of thin films, and therefore it can also be advantageous in coating technologies and material processing. Our results reveal that increasing the volume fraction parameters (phi_1) and (phi_2) results in a thicker thermal boundary layer in both steady and unsteady states. Higher values of (phi_1) and (phi_2) enhance the (phi_1) velocity profile while reducing the (phi_2) velocity profile for both steady and unsteady states of TiO(_2)/SiO(_2)–water/Eg((50,{:},50)) hybrid nanofluid. The results show that thermal conductivity performance of the hybrid nanofluid model is efficient compared with a single nanofluid. ","PeriodicalId":797,"journal":{"name":"Theoretical and Mathematical Physics","volume":"223 3","pages":"1000 - 1015"},"PeriodicalIF":1.1,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145145125","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

Dynamics of a three species syn-ecological ammensalsim model: A stochastic approach 三种同生态生态模型的动力学：随机方法

IF 1.1 4区物理与天体物理

Theoretical and Mathematical Physics Pub Date : 2025-06-25 DOI: 10.1134/S0040577925060078

K. Kondala Rao, K. Lakshmi Narayan, G. Ranjith Kumar, K. Ramesh, A. V. Papa Rao

引用次数: 0

Hall current and thermal diffusion effects on an unsteady MHD free convection flow of non-Newtonian fluid 非牛顿流体非定常MHD自由对流的霍尔电流和热扩散效应

IF 1.1 4区物理与天体物理

Theoretical and Mathematical Physics Pub Date : 2025-06-25 DOI: 10.1134/S004057792506011X

Shaik Nazia, B. Seshaiah

{"title":"Hall current and thermal diffusion effects on an unsteady MHD free convection flow of non-Newtonian fluid","authors":"Shaik Nazia, B. Seshaiah","doi":"10.1134/S004057792506011X","DOIUrl":"10.1134/S004057792506011X","url":null,"abstract":" We investigate the effects of Joule combustion, Hall current, and thermal dispersion on an unstable MHD free convection heat and mass transfer revolving flow of a dense, indestructible, and electrically conducting second-grade fluid that is passing through an exponential plate embedded in a porous medium. This flow was realized in the context of a heat source and viscous dissipation. By the perturbation approach, it is possible to obtain an accurate analytic solution of the governing equations for the fluid velocity, fluid temperature, and species concentration. This solution is obtained while taking the proper initial and boundary conditions into consideration. With the assistance of the MATLAB program, graphical representations are provided for the numerical values of the main and secondary fluid velocities, the temperature of the fluid, and the concentration of the species. The shear stresses, the Nusselt number, and the Sherwood number are calculated analytically, rendered computationally in a tabular style, and discussed with regard to the most important factors with the purpose of satisfying engineering curiosity. The results reveal that an increase in the Hall current parameter enhances the primary velocity while reducing the secondary velocity. Additionally, the thermal diffusion parameter increases the species concentration, while the Schmidt number reduces it due to lower mass diffusivity. These findings have practical applications in industrial processes involving magnetohydrodynamic systems, such as cooling systems for rotating machinery, and in geophysical fluid dynamics for analyzing flows in porous media under thermal and magnetic influences. ","PeriodicalId":797,"journal":{"name":"Theoretical and Mathematical Physics","volume":"223 3","pages":"974 - 991"},"PeriodicalIF":1.1,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145145140","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

Study of a flat universe using the FRW model 用FRW模型研究平坦宇宙

IF 1.1 4区物理与天体物理

Theoretical and Mathematical Physics Pub Date : 2025-06-25 DOI: 10.1134/S004057792506008X

A. Shyam, G. Sarma, B. B. Bora

{"title":"Study of a flat universe using the FRW model","authors":"A. Shyam, G. Sarma, B. B. Bora","doi":"10.1134/S004057792506008X","DOIUrl":"10.1134/S004057792506008X","url":null,"abstract":" We explore the Friedmann–Robertson–Walker cosmological model within the context of Lyra geometry, with a particular focus on the deceleration parameter expressed in terms of the Hubble parameter, (q = - frac{Rddot{R}}{dot{R^{2}}} = - Bigl( frac{dot{H} + H^{2}}{H^{2}} Bigr) = b (mathrm{const})), and the equation of state in the form (P = gammarho). The Lyra geometry, an extension of Riemannian geometry, introduces a gauge function that modifies the conventional metric, potentially offering novel insights into cosmological phenomena. We investigate the impact of this geometry on the dynamics of the universe by analyzing the behavior of the deceleration parameter, which indicates the rate of change of the universe’s expansion. Our findings demonstrate that the incorporation of Lyra geometry significantly influences the deceleration parameter, suggesting new possibilities for understanding cosmic acceleration and the transition from deceleration to acceleration phases. This work enhances our understanding of the universe’s evolution and provides a platform for future research into alternative geometric frameworks in cosmology. ","PeriodicalId":797,"journal":{"name":"Theoretical and Mathematical Physics","volume":"223 3","pages":"952 - 959"},"PeriodicalIF":1.1,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145145146","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