Science topic

Convection - Science topic

Transmission of energy or mass by a medium involving movement of the medium itself. The circulatory movement that occurs in a fluid at a nonuniform temperature owing to the variation of its density and the action of gravity. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed; Webster, 10th ed)
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A model-based framework is presented to predict monoclonal antibody (mAb) pharmacokinetics (PK) in humans based on in vitro measures of antibody physiochemical properties. A physiologically based pharmacokinetic (PBPK) model is used to explore the predictive potential of 14 in vitro assays designed to measure various antibody physiochemical propert...
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The intra-seasonal variation in precipitation isotopes shows a characteristic declining trend over northeast India. As of now, no mechanism offers a consistent explanation of this trend. We have performed the isotopic analysis of precipitation (rain) and estimated net ecosystem exchange and latent heat fluxes using an eddy-covariance system in nort...
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In this paper, we present a mesh adaptation algorithm for the unsteady compressible Navier-Stokes equations under the framework of local discontinuous Galerkin methods coupled with implicit-explicit Runge-Kutta or spectral deferred correction time discretization methods. In both of the two high order semi-implicit time integration methods, the conv...
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Marangoni effect plays an important role in many industrial applications where a surface tension gradient induces fluid flow, e.g., the cleaning process of silicon wafers and the welding process of melted metal. Surface tension gradient can also be caused by a spatially varying temperature field which, in the absence of gravity, is solely responsib...
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The present work aimed to examine the performance of a thermoelectric generator (TEG) augmented with a hydronic evacuated tube solar collector heat exchanger used to heat a cold zone. TEGs were operated on the temperature difference between hot water circulated through the heat exchanger and the cold temperature of the surrounding space. The setup...
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A personal microclimate management system is designed to maintain thermal comfort which allows people to overcome a harsh environment. It consists of several micro-fans placed in the garment side seam to provide cooling air. The computational fluid dynamics method was used to simulate the three-dimensional model and analysis the influence of fan’s...
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Mixed convective heat transfer and pressure drop penalty of nanofluids flow in an isothermal horizontal tube are numerically examined in developed flow region. The study examines three types of nanofluids, simple nanofluids ([Water]/ Al2O3, TiO2, and Cu), Hybrid nanofluids ([Water]/ Al2O3 + Cu), and Ionic nanofluids ([C4mim] [NTf2]/ Al2O3). Richard...
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The paper presents an extensive review on the fundamentals of drying, represented by drying kinetics, and models of some building materials and their importance as highlighted in several studies presented by researchers in this area. The objective of the review is to present gaps and existing approaches that will serve as reference pool for researc...
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A disastrous cloudburst and associated floods in Kerala during the 2019 monsoon season raise the hypothesis that rainfall over the west coast of India, much of which is stratiform, may be trending towards being more convective. As a first exploration, we sought statistically significant differences in monthly ERA-5 reanalysis data for the monsoon s...
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In this article, the heat transfer and flow pattern characteristics are restudied in the proximity of convective boundary condition for three kinds of nanoliquids, namely copper oxide-water nanoliquid (CuO-H 2 O), silver-water nanoliquid (Ag-H 2 O), and titanium dioxide-water nanoliquid (TiO 2-H 2 O). The thermal radiation impact is assumed into ac...
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In this paper, we present a numerical study along with an exhaustive adsorption investigation in a binary dilute mixture model nearby the solvent’s critical point in a configuration relevant for soil remediation. By means of this model, mass and heat transfer efficiency were qualitatively and quantitatively discussed through this work. The converge...
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Commercial freezers are commonly used the outer wall as a heatsink. This heatsink needs surrounded ambient air for cooling, which is the natural convection mechanism. However, in theory the force convection provides more heat transfer than the natural convection. Therefore, energy consumption of the force convection is generally less than the natur...
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Miscible displacements are involved in many applications, including enhanced oil recovery and groundwater remediation. When a less viscous and miscible fluid displaces another more viscous one, an unstable front occurs, and its evolution is controlled by the interplay between diffusion and convection. Much of the research has focused on the instabi...
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With the increase of the application scale of renewable energy low-temperature heating system, it is becoming an inevitable requirement to design a new-type heating terminal with good thermal performance, flexible adjustment, and high combination with buildings. In this study, an enhanced convection-radiant wall panel with orifices (CRWPO) is desig...
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A nonlinear one-dimensional mathematical model of a thermal breakdown of an electrical insulation having the shape of a hollow circular cylinder caused by the difference of the electric potentials on the cylindrical surfaces is constructed. The cylinder is made of the material that is a composite with a polymer matrix modified by dispersed inclusio...
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We study a shape optimization problem involving a solid $$K\subset {\mathbb {R}}^n$$ K ⊂ R n that is maintained at constant temperature and is enveloped by a layer of insulating material $$\Omega $$ Ω which obeys a generalized boundary heat transfer law. We minimize the energy of such configurations among all $$(K,\Omega )$$ ( K , Ω ) with prescrib...
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Hybrid plasma transferred arc (PTA)-laser additive manufacturing (AM) has the potential to build large-scale metal components with high deposition rate and near-net shape. However, the process is complex with many parameters adjustable for process control, which determine the thermal behaviour and thus the final structure and properties of the depo...
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The cooling performance of biological water-silver nanofluid (NF) in three double-pipe heat exchangers with converging sinusoidal inner wall (SCDHX), converging inner wall (CDHX), and plain inner wall (PDHX) was examined numerically using the first and second laws of thermodynamics. The two-phase mixture model is employed to conduct the simulations...
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In this paper we study anisotropic weighted (p, q)-equations with a parametric right-hand side depending on the gradient of the solution. Under very general assumptions on the data and by using a topological approach, we prove existence and uniqueness results and study the asymptotic behavior of the solutions when both the q(·)\documentclass[12pt]{...
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We study a class of non-linear parabolic systems relevant in turbulence theory. Those systems can be viewed as simplified versions of the Prandtl one-equation and Kolmogorov two-equation models of turbulence. We restrict our attention to the case of one space dimension. We consider initial data for which the diffusion coefficients may vanish. We pr...
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In this paper, we construct a high order weighted essentially non-oscillatory (WENO) finite difference discretization for compressible Navier-Stokes (NS) equations, which is rendered positivity-preserving of density and internal energy by a positivity-preserving flux splitting and a scaling positivity-preserving limiter. The novelty of this paper i...
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Heat is a branch of thermodynamics that occupies a unique position due to its involvement in the field of practice. Being linked to the management, transport and exchange of energy in thermal form, it impacts all aspects of human life and activity. Heat transfers are, by nature, classified as conduction, convection (which inserts conduction into fl...
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A theory of stable dendrite growth in an undercooled binary melt is developed for the case of intense convection. Conductive heat and mass transfer boundary conditions are replaced by convective conditions, where the flux of heat (or solute) is proportional to the temperature or concentration difference between the surface of the dendrite and far f...
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This study aimed to experimentally investigate the effects of Al2O3-water nanofluids with six different volume concentrations (0.02%, 0.1%, 0.2%, 0.4%, 0.6%, and 0.8%) instead of water as working fluid on heat transfer and pressure drop on the tube side of a mini-channel shell and tube heat exchanger (MC-STHE). The shell-side hot fluid flow rate wa...
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In propulsion and power systems, operating pressures are increasing to improve cycle efficiency, often reaching conditions that approach or exceed the thermodynamic critical pressure of the working fluid. A known phenomenon that occurs at supercritical pressures is supercritical heat transfer deterioration (HTD). Although this phenomenon is well st...
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In the present study, the influence of numerical analysis involves the transfer of heat for moving fin under convection and radiation with fluid properties depending on internal heat generation is considered. The temperature field for the fin is derived based on the defined geometry. This is transformed into a linear model as per the boundary condi...
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This study is a study of three‐dimensional couple stress Casson fluid flow with nonlinear thermal radiation and heat source effects. The convective heat and mass transfer analysis is applied to a porous stretching sheet. In fluid flow direction, a uniform magnetic field can be applied. Using the similarity transformations, nondimensional expression...
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The present study elucidates the magnetohydrodynamics boundary layer free convective stagnation‐point flow toward an inclined nonlinearly stretching sheet embedded in a porous medium. The recent search explores the consequence of permeability of the medium, thermal as well as mass buoyancy, most importantly obliqueness, and thermal slip at the boun...
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In this investigation, the problem of the study is the effect of the magnetic field and viscous dissipation on heat transfer flow through a moving wedge in the existence of the internal heat generation/absorption and also suction/injection. The governing equations are changed to some coupled nonlinear differential equations with aid of similarity v...
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The present study investigates the mixed convective hybrid nanofluid flow over a rotating sphere under the impact of nonlinear thermal radiation. A model is built to examine the heat transport performance of ferrimagnetic magnetite and copper nanoparticles over a rotating sphere. Nonsimilar transformations are used to nondimensionalize the coupled...
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In this article, we investigate a transient magnetohydrodynamic convective micropolar fluid flow over a semi‐infinite vertical plate embedded in a porous medium in the presence of chemical reaction and thermal diffusion. The dimensionless governing equations are solved by adopting the regular perturbation technique. The impact of various parameters...
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This study deals with an analysis of the time‐dependent dynamics of micropolar fluid flow subject to Lorentz force, diffusion thermal, and viscous dissipation effect past a uniformly moving semi‐infinite porous plate in the presence of chemical reaction. Expressions of velocity, microrotation, concentration, temperature, skin friction, Sherwood num...
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Internal heat modulation has several applications in nuclear reactor design and safety, as well as meteorology. In this paper, the influence of internal heat modulation on Rayleigh–Bénard convection in a Boussinesq–Stokes ferromagnetic fluid is explored using linear and nonlinear analyses. The impact of the square, sine, triangular, and sawtooth wa...
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The present work investigates the thermophoresis and Brownian motion effects in nanofluid flow over a curved stretching sheet (CSS). Also, the Cattaneo–Christov heat flux and Stefan blowing (SB) conditions are considered for studying heat and mass transport characteristics. The present work's novelty is associated with considerations of convective...
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The passive micromixer is one of the essential devices that can be integrated into the Lab on Chip (LoC) system. Micromixer is needed to increase mixing efficiency. In this paper, two Koch fractal obstacle-based micromixer models of Secondary Snowflakes Fractal Micromixer (SSFM) and Tertiary Snowflakes Fractal Micromixer (TSFM) were designed. The e...
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In this paper, magnetohydrodynamic hybrid nanofluid is considered to study the heat transfer performance due to stretching of inclined surface. The stretching surface is considered under the effects of magnetic field along the normal direction. The surface is inclined such that it makes an angle of 450\documentclass[12pt]{minimal} \usepackage{amsma...
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Microwave roasting of cocoa beans was studied as an alternative toward convection roasting. The impact of each roasting treatment was assessed based on roasting degree indicators (moisture content, color, tetramethylpyrazine/trimethylpyrazine ratio), microstructural changes as visualized by cryogenic scanning electronic microscopy (cryo-SEM) and th...
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In this study, two distinct nanoparticles: aluminum oxide (Al2O3) and copper (Cu) are chosen as nanomaterials to examine the effects of nonlinear electrically conducting magnetohydrodynamic radiation on the flow of tangential hyperbolic hybrid nanofluid across a nonlinearly stretched sheet with convective boundary conditions. The equations that reg...
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The current article focuses on mass and thermal transfer analysis of a two‐dimensional immovable combined convective nanofluid flow including motile microorganisms with temperature‐dependent viscosity on top of a vertical plate through a porous medium, and a model has been developed to visualize the velocity slip impacts on a nonlinear partial symb...
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During this exploration, Casson nanofluid is taken over a sheet that is curved and stretching in nature and its flow equations are analyzed. Radiation and slip provisions are also taken into consideration. A magnetic field of uniform rate is provided. Convective heat and mass transference extract dominant conclusions from the system. The Brownian m...
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The Dufour and Soret impacts on magnetohydrodynamic Carreau nanoliquid past a nonlinearly stretching sheet are investigated. Variations in viscosity, heat conductivity, and convective boundary conditions are considered. Suitable similarity conversions are utilized to design the governing equations nondimensional. The Optimal Homotopy Analysis Metho...
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In this paper, the steady/transient magnetohydrodynamics heat transfer within a radiative porous channel due to convective boundary conditions is considered. The solution of the steady‐state and that of the transient version were conveyed by the perturbation and finite difference methods, respectively. The heat transfer mechanism of the present wor...
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A numerical study is performed to explore the effects on heat convection and entropy gthe eneration due to porous stratum and heated block in an enclosure saturated with micropolar hybrid nanofluid. Constant heat flux through half of the length of the square enclosure is centrally placed at the bottom wall and the top wall is isothermally cooled wh...
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The impacts of MHD and heat generation/absorption on lid‐driven convective fluid flow occasioned by a lid‐driven square enclosure housing an elliptic cylinder have been investigated numerically. The elliptic cylinder and the horizontal enclosure boundaries were insulated and the left vertical lid‐driven wall was experienced at a fixed hot temperatu...
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The present level of literature on the subject matter indicates that nothing is known on the heat transfer across the couple stress rheological fluid flowing over a vertical avenue with Robin (mixed) wall conditions. The obtained conservation equations of the model are solved through DTM (differential transform method) and RPM (regular perturbation...
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In this study, we numerically examine the unsteady two‐dimensional natural convective heat transfer flow problem in a corrugated enclosure containing an electrically conducting fluid whose top wall is nonuniformly heated. The vertical sidewalls of the corrugated enclosure are kept isothermally cold, while square‐shaped undulations at the bottom wal...
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In this manuscript, phase change material (PCM), as a thermal energy storage medium, is considered within a 3D wavy cubic enclosure to investigate the effect of free and mixed convection heat transfer on the PCM melting process. Rotating cylinders also are located in the middle of the enclosure to study the effect of their angular velocity in diffe...
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The present work integrates and expands the line of inquiry started in Inam and Lappa (2021), Int. J. of Heat and Mass Transfer, 173, 121267 for unsteady mixed forced-buoyancy convection in a channel with a forward facing step by addressing the mirror case where the fluid flowing in a duct undergoes a sudden expansion (i.e., a channel with a backwa...
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In this paper, we study the effects of rotational modulation on heat and mass transport due to double‐diffusive magnetoconvection in an electrically conducting fluid. In the study, different modes of rotational modulation are considered. Using a perturbation method, a Ginzburg–Landau equation which is nonautonomous is obtained for the modulation am...
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This study investigates heat and mass transfer in MHD convective flow through a vertical plate via porous media in the presence of radiation and a heat source/sink. It is assumed that a uniform magnetic field of strength is imposed perpendicular to the plate and directed into the fluid area. The governing nondimensional equations are solved using t...
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Addressing the second‐grade nanofluid flow over a porous stretching sheet based on entropy generation is done in this study. In the mathematical modeling, the revised Buongiorno model is utilized. Employing exponential space‐dependent heat generation and Heat transfer subject to melting effect is implemented. Energy and concentration expressions ar...
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In this paper, we study the the following problem 0.1-ΔNu-μΔpu=λ(ur+a|∇u|s)+f(x,u)inΩ,u>0inΩ,u=0on∂Ω.\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\begin{aligned} {\l...
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Turbulent superstructures in horizontally extended three-dimensional Rayleigh–Bénard convection flows are investigated in controlled laboratory experiments in water at Prandtl number ${Pr}=7$ . A Rayleigh–Bénard cell with square cross-section, aspect ratio $\varGamma =l/h=25$ , side length $l$ and height $h$ is used. Three different Rayleigh number...
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Large-scale coherent rolls are observed frequently in unstably stratified turbulent wall-bounded flows where they influence strongly the turbulent transport and the mean flow properties. Here we address the question of their genesis by means of a linear stability analysis of the turbulent mean flow where a model of turbulent Reynolds stresses is em...
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Plain Language Summary The effects of human‐caused climate change are becoming more apparent, with weather related natural disasters occurring more frequently each year. In tropical regions, these changes can have far reaching consequences through changes to a large‐scale circulation that transports heat and moisture from the equator to higher lati...