scholarly journals Irreversibility analysis in dissipative magnetohydromagnetic flow of non-Newtonian nanomaterials

2021 ◽  
Vol 11 ◽  
pp. 184798042110564
Author(s):  
Tasawar Hayata ◽  
Zobia Kainata ◽  
Sohail A Khana ◽  
Ahmed Alsaedi
Keyword(s):  
Thermal Field ◽  
Energy Equation ◽  
Entropy Rate ◽  
Stretching Surface ◽  
Bingham Number ◽  
Mass Transport Rate ◽  
Field Velocity ◽  
Influential Parameters ◽  
Magnetic Variable ◽  
Binary Reaction

The theme of this article is to scrutinize the entropy rate in hydromagnetic flow of Reiner–Philippoff nanofluid by a stretching surface. Energy equation is developed through first law of thermodynamic with dissipation and Joule heating. Furthermore, random and thermophoretic motion is discussed. Additionally, binary reaction is discussed. Physical feature of irreversibility analysis is discussed. Nonlinear expression is obtained by suitable transformation. The obtained systems are solved through the numerical method (bvp4c). Variation of entropy rate, thermal field, velocity profile, and concentration against sundry variables are discussed. Computational outcomes of thermal and mass transport rate for influential parameters are studied in tabularized form. A reverse effect holds for thermal field and velocity through magnetic variable. Higher Bingham number leads to a rise in velocity field. An intensification in thermal field and concentration is noted for thermophoretic variable. An enhancement in fluid variable leads to augments velocity. An increment in entropy analysis is seen for magnetic effect. Larger estimation of diffusion variable improves entropy rate. A reduction in concentration is noticed for reaction variable.

Effects of chemically reactive and thermally radiative MHD Prandtl nanofluid by a vertically heated stretchable surface with convective conditions

2021 ◽  
Author(s):  
Haroon Ur Rasheed ◽  
Saeed Islam ◽  
Zeeshan Khan ◽  
Waris Khan
Keyword(s):  
Thermal Field ◽  
Flow Model ◽  
Concentration Field ◽  
Transverse Magnetic ◽  
Nonlinear Pdes ◽  
Stretching Surface ◽  
Force Coefficient ◽  
Convective Boundary ◽  
Nanoparticles Concentration ◽  
Systems Of Odes

Abstract The existing investigations purpose to disclose the interaction effects of transverse magnetic and hydrodynamic flow of Prandtl nanofluid subjected to convective boundary conditions over a vertical heated stretching surface. Developing a fundamental flow model, a boundary layer approximation is done, which yields momentum, concentration, and energy expressions. Moreover, Brownian effect and thermophoresis influence are also taken into the account. The constitutive flow laws of nonlinear (PDEs) is altered into ordinary one via similarity transformation variables. The dimensionless nonlinear systems of (ODEs) are then solved through bvp4c numerical algorithm. Consequences of innumerable flow factors on steam wise velocity, thermal field, and concentration of nanoparticle are explicitly debated and plotted graphically. The drag force coefficient and heat transference rate are assumed and deliberated accordingly. It has been perceived that f higher estimation of thermophoresis parameter upsurges the internal thermal energy of the nanofluid and nanoparticles concentration field.

Dynamics of Thermal Field and Powder Sublimation in an Inductively Heated AlN Bulk Crystal Growth Process

2004 ◽  
Author(s):  
Bei Wu ◽  
Hui Zhang
Keyword(s):  
Crystal Growth ◽  
Maxwell Equations ◽  
Thermal Field ◽  
Energy Equation ◽  
Dynamic Responses ◽  
Transient Temperature ◽  
Bulk Crystal Growth ◽  
Transient Temperature Distribution ◽  
Growth System ◽  
Sublimation Growth

In this paper, an integrated model considering induction heating, transient heat transfer and crystal growth has been developed to study dynamic response of temperature and powder sublimation in an aluminum nitride (AlN) growth system. The electromagnetic field and induction heat generation are calculated by the Maxwell equations. Transient temperature distribution in the growth chamber is simulated by energy equation accounting for conduction/radiation within and between various components. In order to provide proper temperature control during sublimation growth, dynamic responses of temperature and temperature difference of the bottom and top external surfaces of the growth crucible to power variation and coil position movement are simulated. Finally the crystal and powder shapes as a function of time are predicted and compared with dynamic experimental observation.

Soret and Dufour Effects in the Flow of Williamson Fluid over an Unsteady Stretching Surface with Thermal Radiation

2015 ◽  
Vol 70 (4) ◽  
pp. 235-243 ◽  
Author(s):  
Tasawar Hayat ◽  
Yusra Saeed ◽  
Sadia Asad ◽  
Ahmed Alsaedi
Keyword(s):  
Thermal Radiation ◽  
Energy Equation ◽  
Physical Parameters ◽  
Stretching Surface ◽  
Soret And Dufour Effects ◽  
Williamson Fluid ◽  
Linear Ordinary Differential Equations ◽  
Boundary Layer Equations ◽  
Unsteady Stretching Surface ◽  
Biot Numbers

AbstractThis paper looks at the simultaneous effects of heat and mass transfer in the flow of Williamson fluid over an unsteady stretching surface. The effects of thermal radiation and viscous dissipation are considered in an energy equation. Besides, the energy and concentration equations are coupled with the combined effects of Soret and Dufour. The convective conditions for both temperature and mass concentration are employed. The transformation procedure reduces the time-dependent boundary layer equations of momentum, energy, and concentration to the non-linear ordinary differential equations. Through graphs and numerical values, the velocity, temperature, and concentration fields are discussed for different physical parameters. It is found that the thermal and concentration Biot numbers have an increasing impact on both temperature and concentration fields, respectively.

Simulation of Grain Growth During Directional Annealing

1994 ◽  
Vol 362 ◽  
Author(s):  
N. Zacharopoulos ◽  
E. A. Holm ◽  
D. J. Srolovitz
Keyword(s):  
Grain Growth ◽  
Thermal Field ◽  
Finite Size ◽  
Cold Zone ◽  
Simulation Procedure ◽  
Axis Parallel ◽  
Growth Laws ◽  
Field Velocity ◽  
Very High ◽  
Hot Zone

AbstractA Monte Carlo simulation procedure is applied to simulate non-uniform grain growth during directional annealing. The assumed temperature profile consists of a small, finite size hot zone which blends smoothly into cold zones ahead and behind the hot zone. The hot zone is assumed to move with a constant velocity. The influence of the ratio of hot zone to cold zone temperatures and the velocity of the temperature field are investigated. The grain size is analyzed as a function of these variables. We find that very high aspect ratio grains (long axis parallel to the thermal field velocity vector) are possible within a restricted velocity window. These results are analyzed in terms of an analytic model based upon conventional grain growth laws.

Momentum and Heat Transfer on a Continuous Moving Surface

1986 ◽  
Vol 108 (3) ◽  
pp. 532-539 ◽  
Author(s):  
D. R. Jeng ◽  
T. C. A. Chang ◽  
K. J. De Witt
Keyword(s):  
Heat Transfer ◽  
Surface Temperature ◽  
Energy Equation ◽  
Local Heat ◽  
Surface Velocity ◽  
Stretching Surface ◽  
Moving Surface ◽  
Isothermal Surface ◽  
Momentum And Heat Transfer ◽  
Local Heat Flux

An analysis has been carried out to determine the momentum and heat transfer occurring in the laminar boundary layer on a continuous moving surface which has an arbitrary surface velocity and nonuniform surface temperature. Merk series types of solutions are obtained for the momentum and heat transfer for an isothermal surface. The results are expressed in terms of universal functions. For a nonisothermal surface, the procedure begins with a consideration of the solution of the energy equation for a step discontinuity in the surface temperature by the introduction of appropriate transformation variables. Equations for the temperature profile and for the local heat flux are expressed explicitly in terms of the Prandtl number and the surface velocity parameter. Numerical examples for a power law surface velocity and a linearly stretching surface velocity with nonzero slot velocity are given for the isothermal surface. The accuracy of the present solutions is also discussed.

scholarly journals Can we constrain the dark energy equation of state parameters using configuration entropy?

2019 ◽  
Vol 492 (3) ◽  
pp. 3928-3939
Author(s):  
Biswajit Das ◽  
Biswajit Pandey
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Energy Equation ◽  
State Parameter ◽  
Entropy Rate ◽  
Configuration Entropy ◽  
Energy Models ◽  
Equation Of State Parameter ◽  
Best Fitting ◽  
Dynamical Dark Energy

ABSTRACT We propose a new scheme for constraining the dark energy equation of state parameter/parameters based on the study of the evolution of the configuration entropy. We analyse a set of one-parameter and two-parameter dynamical dark energy models and find that the derivative of the configuration entropy in all the dynamical dark energy models exhibits a minimum. The magnitude of the minimum of the entropy rate is decided by both the parametrization of the equation of state and the associated parameters. The location of the minimum of the entropy rate is less sensitive to the form of the parametrization but depends on the associated parameters. We determine the best-fitting equations for the location and magnitude of the minimum of the entropy rate in terms of the parameter/parameters of the dark energy equation of state. These relations would allow us to constrain the dark energy equation of state parameter/parameters for any given parametrization provided the evolution of the configuration entropy in the Universe is known from observations.

On the Inhomogeneity of Chemical Composition over the Surface of 21 Per

1976 ◽  
Vol 32 ◽  
pp. 343-349
Author(s):  
Yu.V. Glagolevsky ◽  
K.I. Kozlova ◽  
V.S. Lebedev ◽  
N.S. Polosukhina
Keyword(s):  
Chemical Composition ◽  
Spectral Line ◽  
Variable Star ◽  
Radial Velocities ◽  
Crimean Astrophysical Observatory ◽  
Line Intensities ◽  
Magnetic Variable

SummaryThe magnetic variable star 21 Per has been studied from 4 and 8 Å/mm spectra obtained with the 2.6 - meter reflector of the Crimean Astrophysical Observatory. Spectral line intensities (Wλ) and radial velocities (Vr) have been measured.

THERMAL FIELD DESORPTION

1989 ◽  
Vol 50 (C8) ◽  
pp. C8-9-C8-14
Author(s):  
H. J. KREUSER ◽  
L. C. WANG
Keyword(s):  
Thermal Field ◽  
Field Desorption

About definition of the local entropy rate of production in experiment of pulse electric heating

2020 ◽  
pp. 29-34
Author(s):  
Alexandr V. Kostanovskiy ◽  
Margarita E. Kostanovskaya
Keyword(s):  
Thermal Diffusivity ◽  
Electric Heating ◽  
Thermal Capacity ◽  
Entropy Rate ◽  
Initial Time ◽  
Local Entropy ◽  
Linear Mode ◽  
Electric Capacity ◽  
Definition Of ◽  
Pulse Electric

Work is devoted to studying of a linear mode thermodynamic – a mode which is actively investigated now. One of the main concepts of a linear mode – local entropy rate of production. The purpose of given article consists in expansion of a circle of problems for which it is possible to calculate a local entropy rate of production, namely its definition, using the experimental “time-temperature” curves of heating/cooling. “Time-temperature” curves heating or cooling are widely used in non-stationary thermophysical experiments at studying properties of substances and materials: phase transitions of the first and second sort, a thermal capacity, thermal diffusivity. The quantitative substantiation of the formula for calculation of the local entropy rate of production in which it is used thermogram (change of temperature from time) which is received by a method of pulse electric heating is resulted. Initial time dependences of electric capacity and temperature are measured on the sample of niobium in a microsecond range simultaneously. Conformity of two dependences of the local entropy rate of production from time is shown: one is calculated under the known formula in which the brought electric capacity is used; another is calculated, using the thermogram.

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