Article
Physics, Multidisciplinary
Waqar Khan Usafzai, Emad H. Aly
Summary: This study presents exact analytical solutions for the two-dimensional laminar jet flow and heat transport of Casson fluid under velocity slip condition. The effects of velocity slip, wall temperature, and mass transfer on the fluid flow and rate of thermal exchange are investigated.
CHINESE JOURNAL OF PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Ling Liu, Jing Li, Shijun Liao
Summary: This study investigates the magnetohydrodynamic flow and heat transfer of a Casson fluid over an exponentially shrinking sheet with suction using the homotopy analysis method. Unlike previous methods, an explicit analytical solution to the nonlinear problem is obtained. The changes in velocity and temperature profiles are studied under different parameter conditions, and the convergent solutions are verified by comparison with numerical results. Analytical formulas are used to analyze the skin friction coefficient and local Nusselt number, providing intuitive insights into the influence of parameters on flow and heat transfer.
Article
Mathematics, Applied
Emad H. Aly, Ulavathi Shettar Mahabaleshwar, Thippeswamy Anusha, Ioan Pop
Summary: In this study, the wall jet problem for a hybrid nanofluid with various factors such as MHD, thermal radiation, velocity slip, and convective boundary conditions was investigated. The governing partial differential equations were transformed into nonlinear ordinary ones and solved theoretically using similarity transformations and hypergeometric functions. The results were compared with those in the literature and showed good agreement. The study also discovered regions of physical solutions and determined dual solutions for the reduced skin friction coefficient by deducing critical and terminated values of the suction/injection parameter.
ZAMM-ZEITSCHRIFT FUR ANGEWANDTE MATHEMATIK UND MECHANIK
(2023)
Article
Physics, Multidisciplinary
Mohammed Alrehili
Summary: The primary goal of this article is to control the mixed convective flow and heat transfer of a non-Newtonian Maxwell nanofluid via a vertically slippery stretched sheet through a porous medium using the Soret and Dufour impact. By studying the Buongiorno model, the mass and thermal characteristics of the nanofluid can be determined. The viscosity alteration of the Maxwell nanofluid with temperature is the main focus of the paper. The mathematical model of the problem is built using the principles of conservation of mass, momentum, and energy, and numerically resolved using the shooting method.
EUROPEAN PHYSICAL JOURNAL PLUS
(2023)
Article
Thermodynamics
Iskandar Waini, Najiyah Safwa Khashi'ie, Abdul Rahman Mohd Kasim, Nurul Amira Zainal, Anuar Ishak, Ioan Pop
Summary: This paper examines the magnetic effects on Reiner-Philippoff fluid flow over a permeable shrinking wedge. It is found that the presence of a magnetic field can improve the friction factor and heat transfer performance, while increasing the suction strength has similar effects. However, increasing the Reiner-Philippoff fluid parameter lowers the heat transfer rate but increases the friction factor.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2022)
Article
Materials Science, Multidisciplinary
Dezhi Yang, Muhammad Israr Ur Rehman, Aamir Hamid, Saif Ullah
Summary: The study investigated the effect of a non-uniform heat source/sink on the unsteady stagnation point flow of Carreau fluid past a permeable stretching/shrinking sheet, incorporating additional effects of magnetohydrodynamics, joule heating, and viscous dissipation. The nonlinear partial differential equations were transformed into ordinary differential equations and solved using the Runge-Kutta-Fehlberg technique. The results showed how the fluid flow velocity and temperature of Carreau fluid varied with different parameters, and how the local Nusselt number changed with the Eckert number for both upper and lower branches.
Article
Thermodynamics
Waqar Khan Usafzai, Emad H. Aly
Summary: This study investigates the interaction of Hiemenz stagnation-point flow with a flexible surface that exhibits linear stretching/shrinking. The flow is controlled by parameters such as wall velocity, gyration velocity, transpiration, and velocity slip. Different values of the stretching/shrinking strength parameter (c) yield multiple exact solutions. Dual solutions are found for skin friction, couple stress friction, and temperature gradient. The number and formation of solutions are dependent on a parameter measuring the correlation between the external flow strength and the surface stretching/shrinking parameter. Exact solutions are derived for different special cases involving uniform surface temperature and linearly growing wall temperature.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2023)
Article
Mathematics
Iskandar Waini, Anuar Ishak, Ioan Pop
Summary: This paper examines the influence of hybrid nanoparticles on flow and heat transfer over a permeable non-isothermal shrinking surface, considering radiation and MHD effects. Results show that heat transfer rate increases with magnetic parameter and radiation parameter, and is higher on isothermal surfaces.
Article
Multidisciplinary Sciences
Mehari Fentahun Endalew, Subharthi Sarkar
Summary: This study investigates the combined impacts of melting process and wedge angle entity on hydromagnetic hyperbolic tangent nanofluid flow. A mathematical model is used to represent the system and numerical computations are carried out using a MATLAB solver. The results show good agreement with previous studies. This study has practical applications in chemical engineering for coating materials, aerosol manufacturing, and thermal treatment of water-soluble solutions.
SCIENTIFIC REPORTS
(2023)
Article
Multidisciplinary Sciences
Galal M. Moatimid, Mona A. A. Mohamed, Ahmed A. Gaber, Doaa M. Mostafa
Summary: The purpose of this investigation is to study the behavior of the tangent-hyperbolic micropolar nanofluid border sheet across an extending layer through a permeable medium under the influence of a normal uniform magnetic field. The study takes into account temperature and nanoparticle mass transmission, as well as other factors such as Ohmic dissipation, heat resource, thermal radiation, and chemical impacts. The results have important applications in boundary layers and stretching sheet issues, and the innovation lies in combining tangent-hyperbolic and micropolar fluids with nanoparticle dispersal.
SCIENTIFIC REPORTS
(2023)
Article
Multidisciplinary Sciences
Muhammad Nadeem, Imran Siddique, Jan Awrejcewicz, Muhammad Bilal
Summary: This work investigates the heat transfer features and stagnation point flow of Magnetohydrodynamics (MHD) hybrid second-grade nanofluid through a convectively heated permeable shrinking/stretching sheet. The study focuses on the enhancement of heat transfer rate using hybrid nanofluids comprised of Alumina (Al2O3) and Copper (Cu) nanoparticles in Sodium Alginate (SA) as the base fluid. The effects of free convection, viscous dissipation, heat source/sink, and nonlinear thermal radiation are also considered.
SCIENTIFIC REPORTS
(2022)
Article
Thermodynamics
M. Riaz Khan, Mohamed Abdelghany Elkotb, R. T. Matoog, Nawal A. Alshehri, Mostafa A. H. Abdelmohimen
Summary: This article investigates the unsteady radiative two-dimensional stagnation point flow of a Casson fluid along a stretching and shrinking sheet, dependent on mixed convection, convective condition, and the slip condition. The study reveals that friction and heat transfer rates are influenced by various parameters, with heat generation parameter affecting the heat transfer rate. The research findings are deemed innovative and can pave the way for future analyses of non-Newtonian fluids.
CASE STUDIES IN THERMAL ENGINEERING
(2021)
Article
Engineering, Multidisciplinary
Sana Bajwa, Saif Ullah, Ilyas Khan, Md Fayz-Al-Asad
Summary: The study investigates transient incompressible flows of Jeffrey fluids over a permeable, flat, and infinite plate using numerical simulations and analytical solutions to analyze the influence of system parameters on fluid motion.
MATHEMATICAL PROBLEMS IN ENGINEERING
(2021)
Article
Thermodynamics
Santosh Chaudhary, Ajay Singh, Devendra Kumar, Dumitru Baleanu
Summary: In this study, the steady and incompressible MHD movement of a viscous nanofluid past a non-linear stretching plate, considering heat generation and the presence of a permeable medium, was mathematically investigated. The impacts of porosity and heat generation were explored, and numerical solutions were obtained using MATLAB software. The results showed that porous media parameter affected the velocity profile, while the temperature and mass distribution exhibited contrasting responses. The findings of this study can be applied to the design of high-temperature processing operations.
CASE STUDIES IN THERMAL ENGINEERING
(2023)
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
Mustafa Turkyilmazoglu
Summary: This paper extends the classical models for fluid flow, heat transfer, and impulsive acceleration by introducing fractional derivatives. The solutions are represented as steady and transient parts, and alternative solution methods are provided. The findings demonstrate the impact of fractional derivative in different time regimes, contributing to the understanding of diffusion phenomena.
INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW
(2023)
Article
Mathematics, Interdisciplinary Applications
Mustafa Turkyilmazoglu, Mohamed Altanji
Summary: Distinct fractional models of falling object with linear and quadratic air resistive forces are investigated using Caputo fractional derivative. Analytical solutions are obtained for each model, providing a vivid understanding of the object's motion. The contribution of nonlinearity to the fractional models is carefully examined. These fractional models exhibit rich phenomena not found in traditional integer derivative models, but still converge to the traditional model. Short time perturbation and large time asymptotic formulae are derived. The solutions for some fractional models suggest either an increased speed surpassing gravity or asymptotic deceleration to a stop, in contrast to reaching a terminal speed. In the case of quadratic air resistance, power series and asymptotic series solutions are derived under Caputo fractional derivative and infinite base fractional differentiation, respectively. The analysis of ideal falling object motion emphasizes the impact of fractional models and fractional derivative definitions on physical motion, necessitating proper justification.
CHAOS SOLITONS & FRACTALS
(2023)
Article
Thermodynamics
Mustafa Turkyilmazoglu
Summary: The purpose of this work is to study the fluid flow and heat transfer between a rotating cone above a stretching disk. By using suitable similarity transformations, it is found that the physical phenomenon can be represented by a system of similarity equations, which is consistent with the literature in the absence of wall expansion. Numerical simulations are used to study the effects of surface expansion on momentum, thermal layers, swirling angles, and heat transports.
INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW
(2023)
Article
Physics, Applied
Muhammad Rahman, H. Waheed, M. Turkyilmazoglu, M. Salman Siddiqui
Summary: This study focuses on Darcy-Brinkman flow across a stretched sheet in a porous medium, considering dissipation and frictional heating. It examines the geometry and equations governing the steady flow of dust particle fluid with slip effect and porous dissipation. Using similarity transformation, a two-dimensional nonlinear partial differential equation is reduced to a sequence of nonlinear ordinary differential equations. Numerical techniques, such as Maple packages and the RK4 method, are employed to solve the system of nonlinear equations and derive the numerical findings.
INTERNATIONAL JOURNAL OF MODERN PHYSICS B
(2023)
Article
Physics, Applied
Muhammad Rahman, Humma Waheed, Mustafa Turkyilmazoglu, M. Salman Siddiqui
Summary: This paper explores the significance of slip situations in porous media and frictional heating on unsteady fluid flow through porous media. Numerical solutions of the differential equation for fluid flow through porous material, including slip effects, are presented. Using a similarity transformation, a nonlinear ordinary differential equation is obtained. The resulting set of nonlinear problems is numerically solved using Maple packages under velocity and thermal slip conditions. Both velocity and temperature increase with an increase in the Brinkman viscosity ratio parameter ?. The effects of the nondimensional parameters on flow velocity and temperature are examined using graphical profiles. The implications of relevant parameters on dimensionless temperature, velocity, local Nusselt number, and skin friction coefficient are shown and explained. The fluctuation of parameters for various flow quantities of interest is investigated and the results are presented in graphs and tables.
INTERNATIONAL JOURNAL OF MODERN PHYSICS B
(2023)
Article
Thermodynamics
Mustafa Turkyilmazoglu
Summary: This paper investigates the mechanism of triggering Benard convection through the absolute instability mode in the presence of a uniform magnetic field perpendicular to the channel walls. The locus of wavenumbers and critical Rayleigh numbers leading to absolute instability onset is determined through a theoretical linear stability approach. The magnetic field has a stabilizing effect on convection, but it becomes ineffective against the absolute instability mechanism beyond a critical location.
INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW
(2023)
Article
Thermodynamics
Mustafa Turkyilmazoglu, Abuzar Abid Siddiqui
Summary: In this study, the scope is to extend previous work by incorporating the effective viscosity term within the transitional flow in the frame of Brinkman-Darcy-Benard convection. Numerical simulations were performed to investigate the onset of instability within the linear stability analysis, considering the Darcy number, Rayleigh number, and horizontal temperature parameter as essential physical parameters. The results showed that comparatively larger Rayleigh numbers were obtained within the Brinkman's model than the published Darcy model.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Engineering, Chemical
Mustafa Turkyilmazoglu
Summary: This study investigates the onset and formation of Darcy-Bernard convection in a channel filled with fluid-saturated porous medium of finite depth. The Darcy model of porosity is used to identify a new family of solutions controlled by two parameters. These solutions cover most basic states associated with the Darcy law equations. The results reveal the relaxed impermeable wall constraints and provide insight into the triggering/delaying of Darcy-Bernard cells.
TRANSPORT IN POROUS MEDIA
(2023)
Article
Chemistry, Analytical
Mustafa Turkyilmazoglu, Faisal Z. Duraihem
Summary: The paper introduces new tubular shapes resulting from the imposition of Navier's velocity slip at the surface. A family of pipes induced by the slip mechanism is discovered, which modifies traditional pipes with elliptical cross-sections and resembles collapsible tubes. The velocity and temperature fields of the new pipes are analytically determined, and physical features such as wall shear stress and convective heat transfer are studied in detail. The new pipes are considered to have engineering and practical value in the micromachining industry.
Article
Mechanics
Mustafa Turkyilmazoglu
Summary: This paper presents full solutions of the energy and Navier-Stokes equations in the approximate form of Boussinesq. The study focuses on the advective fluid layer flowing within parallel horizontal infinite walls with hydro-thermal slip conditions and the control of momentum/thermal motion by a vertically applied magnetic field. The results show that hydro-thermal slip enhances both velocity and temperature fields, while magnetic field has a weaker suppression effect.
ARCHIVE OF APPLIED MECHANICS
(2023)
Article
Physics, Multidisciplinary
Mustafa Turkyilmazoglu
Summary: Forecasting the epidemic peak time is crucial for making decisions on isolation, social distance, and lockdown measures. This research introduces two formulas for accurately predicting the peak time of an infectious disease based on the SIR epidemic model. These formulas can be easily computed using a regular calculator and do not require advanced mathematical functions. The accuracy of the formulas is confirmed through a comparison with COVID-19 data and the formulas can also accurately capture the past peak time of an endemic illness. Additionally, simple approximations are provided for easy use without sophisticated laboratory equipment.
CHINESE JOURNAL OF PHYSICS
(2023)
Article
Mechanics
Mustafa Turkyilmazoglu, Faisal Z. Duraihem
Summary: Thermally-driven natural convection in a porous layer is explored theoretically in this work based on Darcy's law. The study focuses on the non-circulating basic cellular flow between two infinitely long horizontal plates and its instability onset. The results show that a circulatory flow and temperature variation along the horizontal axis govern the motion, and the instability can be determined through linear stability analysis and numerical calculations.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2024)
Article
Physics, Applied
Muhammad Rahman, Mustafa Turkyilmazoglu, Muhammad Bilal
Summary: This study examines the shape effects of different nanoparticles (sphere, blade, cylinder, and brick) in an incompressible, unsteady flow of a nanofluid Al2O3 with water H2O as the base fluid over a rotating disk. The magnetic field results are also included. The numerical solution of the Navier-Stokes equation, along with the magnetic field effect and the thermal energy equation, is obtained using the Von Karman transformation and the bvp4c MATLAB solver. The graphical illustrations show the effects of various parameters on the velocity field and temperature profile. The analysis is validated by comparison with previous research. Additionally, the volume fraction parameter and the unsteadiness parameter have significant influences on the velocity profiles near the disk for different nanoparticle shapes, while the magnetic field impact is limited by the suction parameter values.
INTERNATIONAL JOURNAL OF MODERN PHYSICS B
(2023)
Article
Materials Science, Multidisciplinary
Mustafa Turkyilmazoglu, Faisal Z. Duraihem
Summary: This paper provides closed form solutions for fluid flow affected by a uniform magnetic field inside a triangular cross section pipe. The governing equation for pressure gradient induced flow under the magnetic field is reduced to a Helmholtz partial differential equation with Dirichlet boundary conditions. The velocity solution is derived using exponential functions involving the magnetic strength parameter or Hartmann number. The effects of Lorentz force on velocity variations, centerline velocity, volumetric flow rate, and wall shears are analyzed graphically by increasing the magnetic field strength.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Muhammad Rahman, Mustafa Turkyilmazoglu, Kiran Matloob
Summary: This research investigates the thermal performance of a hybrid nanofluid consisting of aluminum oxide and copper nanoparticles on the flow of water and ethylene glycol over a permeable cylinder. Different nanoparticle shapes are considered and the effects of different parameters are analyzed. The study reveals the impact of porosity, Hartmann numbers, inertia factors, Prandtl number, stratification parameter, Eckert number, and Hartmann's number on the velocity field and fluid temperature of the hybrid nanofluid.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2023)
Article
Thermodynamics
Mahsa Taghavi, Swapnil Sharma, Vemuri Balakotaiah
Summary: This study investigates the natural convection effects in the insulation layers of spherical storage tanks and their impact on the tanks' performance. The permeability and Rayleigh number of the insulation material are considered as key factors. The results show that as the Rayleigh number increases, new convective cells emerge and cause the cold boundary to approach the external hot boundary. In the case of large temperature differences, multiple solutions may coexist.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinyang Xu, Fangjun Hong, Chaoyang Zhang
Summary: This study introduces a self-induced jet impingement device for enhancing pool boiling performance in high power electronic cooling. Through visualization and parametric investigations, the effects of this device on pool boiling performance are studied, revealing the promotion of additional liquid supply and vapor exhausting. The flow rate of the liquid jet is found to positively impact boiling performance.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Wenchao Ke, Yuan Liu, Fissha Biruke Teshome, Zhi Zeng
Summary: Underwater wet laser welding (UWLW) is a promising and labor-saving repair technique. A thermal multi-phase flow model was developed to study the heat transfer, fluid dynamics, and phase transitions during UWLW. The results show that UWLW creates a water keyhole, making the welding environment similar to in air laser welding.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Xingrong Lian, Lin Tian, Zengyao Li, Xinpeng Zhao
Summary: This study investigates the heat transfer mechanisms in natural fiber-derived porous structures and finds that thermal radiation has a significant impact on the thermal conductivity in low-density regions, while natural convection rarely occurs. Insulation materials derived from micron-sized natural fibers can achieve minimum thermal conductivity at specific densities. Strategies to lower the thermal conductivity include increasing porosity and incorporating nanoscale pores using nanosize fibers.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Yasir A. Malik, Kilian Koebschall, Stephan Bansmer, Cameron Tropea, Jeanette Hussong, Philippe Villedieu
Summary: Ice crystal icing is a significant hazard in aviation, and accurate modeling of sticking efficiency is essential. In this study, icing wind tunnel experiments were conducted to quantify the volumetric liquid water fraction, sticking efficiency, and maximum thickness of ice layers. Two measurement techniques, calorimetry and capacitive measurements, were used to measure the liquid water content and distribution in the ice layers. The experiments showed that increasing wet bulb temperatures and substrate heat flux significantly increased sticking efficiency and maximum ice layer thickness.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinqi Hu, Tongtong Geng, Kun Wang, Yuanhong Fan, Chunhua Min, Hsien Chin Su
Summary: This study experimentally examined the heat dissipation of vibrating fans and demonstrated its inherent mechanism through numerical simulation. The results showed that the flow fields induced by the vibrating blades exhibited pulsating features and formed large-scale and small-scale vortical structures, significantly improving heat dissipation. The study also identified the impacts of different blade structures and developed a trapezoidal-folding blade, which effectively reduced the maximum temperature of the heat source and alleviated high-temperature failure crisis.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Dan-Dan Su, Xiao-Bin Li, Hong-Na Zhang, Feng-Chen Li
Summary: The boiling heat transfer of low-boiling-point working fluid is a common heat dissipation technology in electronic equipment cooling. This study analyzed the interfacial boiling behavior of R134a under different conditions and found that factors such as the initial thickness of the liquid film, solid-liquid interaction force, and initial temperature significantly affect the boiling mode and thermal resistance.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinyi Wu, Dongke Sun, Wei Chen, Zhenhua Chai
Summary: A unified lattice Boltzmann-phase field scheme is proposed to simulate dendrite growth of binary alloys in the presence of melt convection. The effects of various factors on the growth are investigated numerically, and the model is validated through comparisons and examinations.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Shaokun Ge, Ya Ni, Fubao Zhou, Wangzhaonan Shen, Jia Li, Fengqi Guo, Bobo Shi
Summary: This study investigated the temperature distribution of main cables in a suspension bridge during fire scenarios and proposed a prediction model for the maximum temperature of cables in different lane fires. The results showed that vehicle fires in the emergency lane posed a greater thermal threat to the cables.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Shuang-Ying Wu, Shi-Yao Zhou, Lan Xiao, Jia Luo
Summary: This paper investigates the two-phase flow and heat transfer characteristics of low-velocity jet impacting on a cylindrical surface. The study reveals that the heat transfer regimes are non-phase transition and nucleate boiling with the increase of heat transfer rate. The effects of jet impact height and outlet velocity on local surface temperatures are pronounced at the non-phase transition stage. The growth rates of heat transfer rate and liquid loss rate increase significantly from the non-phase transition to nucleate boiling stage.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Emad Hasani Malekshah, Wlodzimierz Wlodzimierz, Miros law Majkut
Summary: Cavitation has significant practical importance and can be controlled by air injection. This study investigates the natural to ventilated cavitation process around a hydrofoil through numerical and experimental methods. The results show that the location and rate of air injection have a meaningful impact on the characteristics of cavitation.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Feriel Yahiat, Pascale Bouvier, Antoine Beauvillier, Serge Russeil, Christophe Andre, Daniel Bougeard
Summary: This study explores the enhancement of mixing performance in laminar flow equipment by investigating the generation of chaotic advection using wall deformations in annular geometries. The findings demonstrate that the combined geometry can achieve perfect mixing at various Reynolds numbers.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Hui He, Ning Lyu, Caihua Liang, Feng Wang, Xiaosong Zhang
Summary: This study investigates the condensation, frosting, and defrosting processes on superhydrophobic surfaces with millimeter-scale structures. The results reveal that the structures can influence the growth and removal of frost crystals, with the bottom grooves creating a frost-free zone and conical edges promoting higher frost crystal heights. Two effective methods for defrosting are observed: hand-lifting the groove and airfoil retraction contraction on protruding structures. This research provides valuable insights into frost formation and defrosting on millimeter-structured superhydrophobic surfaces, with potential applications in anti-frost engineering.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Thiwanka Arepolage, Christophe Verdy, Thibaut Sylvestre, Aymeric Leray, Sebastien Euphrasie
Summary: This study developed two thermal concentrators, one with a 2D design of uniform thickness and another with a 3D design, using the coordinate transformation technique and metamaterials. By structuring the thermal conductor, the desired local density-heat capacity product and anisotropic thermal conductivities were achieved. The homogenized thermal conductivities were obtained from finite element simulations and cylindrical symmetry consideration. A 3D concentrator was fabricated using 3D metal printing and characterized using a thermal camera. Compared to devices that solely consider anisotropic conductivities, the time evolution characteristics of the metadevice designed with coordinate transformation were closer to those of an ideal concentrator.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Liangyuan Cheng, Qingyang Wang, Jinliang Xu
Summary: In this study, we investigated the supercritical heat transfer of CO2 in a horizontal tube with a diameter of 10.0 mm, covering a wide range of pressures, mass fluxes, and heat fluxes. The study revealed a non-monotonic increase in wall temperatures along the flow direction and observed both positive and negative wall temperature differences between the bottom and top tube. The findings were explained by the thermal conduction in the solid wall interacting with the stratified-wavy flow in the tube.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
