Article
Mechanics
Yue Xiao, Bin Zhang, Moli Zhao, Shaowei Wang
Summary: This study examines the instability of the buoyancy-driven boundary layer on a vertical cylinder, providing mathematical descriptions and analytical solutions of the basic flow. Results show the effects of Prandtl number and transversal curvature, with significant differences in unstable modes observed for different Pr values.
Article
Multidisciplinary Sciences
Abdulaziz Alsenafi, M. Ferdows
Summary: The study focused on the steady mixed convection flow towards an isothermal permeable vertical cylinder nested in a fluid-saturated porous medium, applying the Darcy model to observe bioconvection. The results indicated the existence of dual solutions in opposing flow beyond a critical point, where both solutions are connected, influenced by the systems' parameters.
SCIENTIFIC REPORTS
(2021)
Article
Mechanics
K. V. Nagamani, B. M. Shankar, I. S. Shivakumara
Summary: This study investigates the stability of parallel buoyant flow in a vertical layer of Brinkman porous medium with a density maximum and quadratic density law. The linear and quadratic density-temperature relationships are compared in terms of their effects on the base flow, stability features, and mode of instability. It is analytically proven that the base flow remains unconditionally stable if governed by classical Darcy's law, regardless of the density variation with temperature. However, the stability of the base flow is affected by the density-temperature relationship when governed by unsteady Darcy's law or Brinkman-extended Darcy law. The change from linear to quadratic density law leads to instability through a traveling-wave mode within a certain range of Darcy-Prandtl number for unsteady Darcy flow model.
Article
Mechanics
Kapil Dev, Om P. Suthar
Summary: This article presents a numerical analysis of convection induced by the combined effects of buoyancy force and surface tension in industrial applications. The study focuses on the stability and constraints of convection in an anisotropic porous layer with high permeability. The results show that thermal anisotropy and Biot numbers stabilize the system, while mechanical anisotropy and the Darcy number advance the onset of convection. The study also compares the linear and energy analysis results, indicating the possibility of subcritical instabilities.
Article
Mathematics, Applied
Om Prakash Meena, Pranitha Janapatla, Ganesh K. Kumar
Summary: The objective of this study is to investigate the influence of double dispersion on mixed convection flow over a vertical cone of an incompressible viscous fluid saturated porous medium. The non-similarity equations are solved numerically using the bivariate Chebyshev spectral collocation quasi-linearization method. The results show the effects of governing parameters on the velocity, temperature, and concentration profiles, as well as the skin friction, heat, and mass transfer coefficients. A comparison with prior published results validates the accuracy of the computations, and the residual analysis study demonstrates the convergence and stability of the calculations.
APPLIED MATHEMATICS AND COMPUTATION
(2022)
Article
Mechanics
Km Renu, Ashok Kumar, Abhishek K. Sharma
Summary: The study investigated the stably stratified flow in a linearly heated vertical pipe filled with a fluid-saturated porous medium, with a focus on the impact of permeability and Prandtl number on the stability of basic flow at different disturbance modes. The results demonstrate that the least stable mode depends on the values of Pr and Da, with a small range of Pr exhibiting a change in destabilizing characteristics to stabilizing characteristics for certain Da values.
Article
Thermodynamics
R. Hemalatha, Peri K. Kameswaran, P. V. S. N. Murthy
Summary: The current article discusses the mixed convective flow of Graphene oxide and Clay nanoparticles suspended in a nanofluid in a non-Darcy porous medium, taking into account the shape of the nanoparticles. The findings indicate that spherical nanoparticles exhibit an enhanced temperature distribution and have a higher settling rate in the base fluid.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2022)
Article
Engineering, Multidisciplinary
Nepal Chandra Roy
Summary: A mathematical model was developed to analyze the free convection flow induced by catalytic surface reaction on a vertical wavy surface embedded in a non-Darcy porous medium. The numerical results showed that the wall temperature and the surface concentration were affected by different parameters, and the thicknesses of the boundary layers for momentum, heat, and concentration also varied accordingly.
INTERNATIONAL JOURNAL OF NONLINEAR SCIENCES AND NUMERICAL SIMULATION
(2022)
Article
Multidisciplinary Sciences
Sumera Dero, Hisamuddin Shaikh, Ghulam Hyder Talpur, Ilyas Khan, Sayer O. Alharbim, Mulugeta Andualem
Summary: This study investigates the heat transfer properties of magnetized Cu + Al2O3 / water hybrid nanofluid over a shrinking surface, with radiation effects. The numerical solution of the ODE model using the shooting method reveals the existence of dual solutions. Stability analysis identifies the conditions for the presence of dual solutions and emphasizes the impact of the copper solid volume fraction parameter on heat transfer rate.
SCIENTIFIC REPORTS
(2021)
Article
Physics, Multidisciplinary
T. N. Sakshath, C. Hemanth Kumar
Summary: An analytic study conducted on Darcy-Benard convection in a Newtonian liquid-saturated porous medium, with the presence of pressure gradient and heat source, using the local thermal non-equilibrium model (LTNE). The LTNE assumption accelerates the onset of convection and enhances heat transport. The increase in the porosity-modified ratio of thermal conductivity and heat source promotes the onset of convection and increases heat transport, while the remaining parameters show an opposite trend. The LTNE effect ceases at a certain point, and the Darcy-Benard convection results using the LTE model are obtained as a limiting case.
EUROPEAN PHYSICAL JOURNAL PLUS
(2023)
Article
Thermodynamics
P. G. Siddheshwar, Mahesha Narayana, Richa Saha, Smita S. Nagouda
Summary: This paper presents a comparison between the results of three thermoconvective flows of a Newtonian fluid over undulated surfaces and a flat plate in a porous medium. It is found that the shape of the surface has a significant impact on the fluid dynamics and heat transfer, with the flat plate showing smaller effects compared to the undulated surfaces.
JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME
(2022)
Article
Physics, Multidisciplinary
Elsayed M. A. Elbashbeshy, Hamada Galal Asker
Summary: This paper investigates the boundary layer flow of a nanofluid containing gyrotactic microorganisms over a vertical stretching surface embedded in a porous medium. The effects of various controlling parameters on velocity, temperature, nanoparticle concentration, and microorganisms conservation are analyzed numerically. The results show that increasing the porosity parameter enhances the surface cooling effect.
EUROPEAN PHYSICAL JOURNAL PLUS
(2022)
Article
Materials Science, Multidisciplinary
Zia Ullah, Hafeez Ahmad, Aamir Abbas Khan, Musaad S. Aldhabani, Samirah H. Alsulami
Summary: This study numerically investigates the temperature dependent thermal conductivity, surface heat flux, and magnetohydrodynamic effects on electromagnetic fluid across a magnetically vertical surface placed in a porous material. The aligned magnetic field serves as a coating material to insulate the heat and reduce excessive heating, which is crucial in modern technologies. The primary goal is to magnetize the surface and the developed partial differential equations are converted into nonlinear coupled ordinary differential equations using defined stream functions and similarity variables. Numerical outcomes are obtained using the Keller Box approach and presented in graphs and tables with the help of MATLAB program. Physical features such as skin friction, heat transfer, and magnetic flux affect parameters like thermal-conductivity number, Biot number, and porous number, which in turn affect the velocity profile, magnetic field profile, and temperature profile across the magnetically vertical surface. This thermal and magneto hydrodynamics problem is important in fields such as MRI resonance sequences, artificial heart valves, internal heart cavities, and nanoburning technologies.
MATERIALS TODAY COMMUNICATIONS
(2023)
Article
Thermodynamics
Marilize Everts, Mostafa Mahdavi, Mohsen Sharifpur, Josua P. Meyer
Summary: The thermal and hydrodynamic features of developing mixed convective laminar flow in a long horizontal tube were investigated numerically and experimentally. It was found that the conventional understanding of the merging boundary layer in internal tube flows needed modification, and methods were proposed to determine the development of the hydrodynamic and thermal boundary layers. The experimental and numerical results showed that the local mixed convective Nusselt numbers decreased near the tube inlet but increased along the tube length as secondary flow increased significantly.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Mechanics
Kay Schaefer, Bettina Frohnapfel, Juan Pedro Mellado
Summary: Turbulent mixed convection in channel flows with heterogeneous surfaces is studied using direct numerical simulations. The study finds that the heterogeneous surfaces significantly affect the flow structures, especially in the transition from rolls to cells. Additionally, the heterogeneous surfaces result in slow dynamics of the streamwise rolls.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Thermodynamics
N. C. Rosca, A. Rosca, I Pop, J. H. Merkin
HEAT AND MASS TRANSFER
(2020)
Article
Thermodynamics
S. Dutta, S. Bhattacharyya, I. Pop
JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME
(2020)
Article
Thermodynamics
F. O. Patrulescu, T. Grosan, I. Pop
JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME
(2020)
Article
Engineering, Chemical
Anuar Jamaludin, Kohilavani Naganthran, Roslinda Nazar, Ioan Pop
Article
Thermodynamics
Alin V. Rosca, Natalia C. Rosca, Ioan Pop
Summary: This study describes the steady mixed convection stagnation point of a hybrid nanofluid with a second-order velocity slip, using numerical methods to explore dual solutions. The research findings have practical implications for applications in modern industry, such as micro-manufacturing and nano drug delivery systems. The use of a wall slip velocity in the hybrid nanofluid model adds novelty to the study by analyzing the behavior of flow and heat transfer with varying parameters.
INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW
(2021)
Article
Thermodynamics
Iskandar Waini, Anuar Ishak, Ioan Pop
Summary: This paper investigates the flow of a hybrid nanofluid towards a stagnation point on an exponentially stretching/shrinking vertical sheet with buoyancy effects. The authors found that the heat transfer rate is higher for the Al2O3-Cu/water hybrid nanofluid compared to Cu/water nanofluid, and observed non-uniqueness of solutions for certain physical parameters. Additionally, bifurcation of solutions was noticed in the downward buoyant force and shrinking regions.
INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW
(2021)
Article
Thermodynamics
Amin Noor, Roslinda Nazar, Kohilavani Naganthran, Ioan Pop
Summary: This paper investigates the unsteady mixed convection stagnation point flow and heat transfer past a stationary surface in an incompressible viscous fluid numerically. By transforming the governing equations and solving them using numerical methods, the effects of parameters on fluid flow and heat transfer characteristics are illustrated, and the existence of dual solutions is found. This study is relevant to heat exchanger applications in low-velocity environments and the cooling of electronic devices, providing novel numerical results in a previously unstudied scenario.
INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW
(2021)
Article
Thermodynamics
Nurul Amira Zainal, Roslinda Nazar, Kohilavani Naganthran, Ioan Pop
Summary: This study investigates the flow and heat transfer characteristics of hybrid nanofluid on a permeable moving surface in the presence of magnetohydrodynamics and thermal radiation. The results show that the presence of a magnetic field and suction slows down the fluid motion, while an increase in thermal radiation parameter enhances heat transfer rate. Additionally, stability analysis confirms the existence of dual solutions within a specific range of moving parameters, with only one solution being physically relevant.
INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW
(2021)
Article
Thermodynamics
Iskandar Waini, Anuar Ishak, Ioan Pop
Summary: This study examines the effects of Dufour and Soret diffusions on Al2O3-water nanofluid flow over a moving thin needle using the Tiwari and Das model. The analysis focuses on the uniqueness of the solutions for different physical parameters and the implications for skin friction, heat transfer, and mass transfer coefficients.
INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW
(2021)
Article
Thermodynamics
Nur Syazana Anuar, Norfifah Bachok, Ioan Pop
Summary: This paper discusses the stability analysis of Cu-Al2O3/water nanofluid under radiation and suction effects on a rotating stretching/shrinking sheet. The study reveals non-unique solutions for certain shrinking parameter values and significant impact of suction parameter on obtaining solutions. The presence of copper nanoparticle volume fractions results in increased local skin friction and decreased local Nusselt number on the shrinking surface.
INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW
(2021)
Article
Thermodynamics
Mikhail A. Sheremet, Teodor Grosan, Ioan Pop
Summary: This paper numerically studies the steady thermal convection in a chamber filled with a nanoliquid affected by a chemical reaction using the single-phase nanofluid approximation. Various results such as streamlines, isotherms, isoconcentrations, nanofluid flow rate, mean Nusselt and Sherwood numbers are discussed. The originality lies in the investigation of how homogeneous-heterogeneous reactions affect nanoliquid motion and energy transport within enclosures, which has not been explored before.
INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW
(2021)
Article
Thermodynamics
Ubaidullah Yashkun, Khairy Zaimi, Nor Ashikin Abu Bakar, Anuar Ishak, Ioan Pop
Summary: This study investigates the heat transfer characteristics of MHD hybrid nanofluid over a linear stretching and shrinking surface with suction and thermal radiation effects. The study finds that the heat transfer efficiency of the hybrid nanofluid is greater than the nanofluid, and dual solutions exist for a specific range of the stretching/shrinking parameter. Additionally, the skin friction coefficient and local Nusselt number increase with suction effect, and suction and thermal radiation widen the range of the stretching/shrinking parameter for which solutions exist.
INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW
(2021)
Article
Thermodynamics
Mohammad M. Rahman, Kawkab A. Al Amri, Ioan Pop
Summary: This numerical study investigated the convective flow of water, kerosene, and engine oil through different porous media, taking into account thermal stratification. The results showed that the heat transfer rate increases with the Rayleigh number but decreases with thermal stratification, porosity, and aspect ratio of the enclosure.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2021)
Article
Chemistry, Multidisciplinary
Behzad Ebadi, Morteza Behbahani-Nejad, Maziar Changizian, Ioan Pop
KOREAN JOURNAL OF CHEMICAL ENGINEERING
(2020)
Article
Multidisciplinary Sciences
Iskandar Waini, Anuar Ishak, Ioan Pop
SCIENTIFIC REPORTS
(2020)
