scholarly journals Numerical study of radiative non-Darcy nanofluid flow over a stretching sheet with a convective Nield conditions and energy activation

2021 ◽  
Vol 10 (1) ◽  
pp. 159-176
Author(s):  
N. Vedavathi ◽  
Ghuram Dharmaiah ◽  
Kothuru Venkatadri ◽  
Shaik Abdul Gaffar
Keyword(s):  
Numerical Solutions ◽  
Volume Fraction ◽  
Numerical Study ◽  
Similarity Solutions ◽  
Physical Parameters ◽  
Stretching Surface ◽  
Two Phase ◽  
Relevant Variable ◽  
Flow And Heat Transfer ◽  
Metal Spinning

Abstract Numerous industrial processes such as continuous metal casting and polymer extrusion in metal spinning, include flow and heat transfer over a stretching surface. The theoretical investigation of magnetohydro-dynamic thermally radiative non-Darcy Nanofluid flows through a stretching surface is presented considering also the influences of thermal conductivity and Arrhenius activation energy. Buongiorno’s two-phase Nanofluid model is deployed in order to generate Thermophoresis and Brownian motion effects [1]. By similarity transformation technique, the transport equations and the respective boundary conditions are normalized and the relevant variable and concerned similarity solutions are presented to summarize the transpiration parameter. An appropriate Matlab software (Bvp4c) is used to obtain the numerical solutions. The graphical influence of various thermo physical parameters are inspected for momentum, energy and nanoparticle volume fraction distributions. Tables containing the Nusselt number, skin friction and Sherwood number are also presented and well argued. The present results are compared with the previous studies and are found to be well correlated and are in good agreement. The existing modelling approach in the presence of nanoparticles enhances the performance of thermal energy thermo-plastic devices.

scholarly journals Steady and unsteady fluidised granular flows down slopes

2017 ◽  
Vol 827 ◽  
pp. 67-120 ◽  
Author(s):  
D. E. Jessop ◽  
A. J. Hogg ◽  
M. A. Gilbertson ◽  
C. Schoof
Keyword(s):  
Gas Flow ◽  
Numerical Solutions ◽  
Volume Fraction ◽  
Granular Flows ◽  
Similarity Solutions ◽  
Two Phase ◽  
Basal Resistance ◽  
Front Position ◽  
Theoretical Predictions ◽  
Asymptotic Reduction

Fluidisation is the process by which the weight of a bed of particles is supported by a gas flow passing through it from below. When fluidised materials flow down an incline, the dynamics of the motion differs from their non-fluidised counterparts because the granular agitation is no longer required to support the weight of the flowing layer. Instead, the weight is borne by the imposed gas flow and this leads to a greatly increased flow mobility. In this paper, a framework is developed to model this two-phase motion by incorporating a kinetic theory description for the particulate stresses generated by the flow. In addition to calculating numerical solutions for fully developed flows, it is shown that for sufficiently thick flows there is often a local balance between the production and dissipation of the granular temperature. This phenomenon permits an asymptotic reduction of the full governing equations and the identification of a simple state in which the volume fraction of the flow is uniform. The results of the model are compared with new experimental measurements of the internal velocity profiles of steady granular flows down slopes. The distance covered with time by unsteady granular flows down slopes and along horizontal surfaces and their shapes are also measured and compared with theoretical predictions developed for flows that are thin relative to their streamwise extent. For the horizontal flows, it was found that resistance from the sidewalls was required in addition to basal resistance to capture accurately the unsteady evolution of the front position and the depth of the current and for situations in which sidewall drag dominates, similarity solutions are found for the experimentally measured motion.

scholarly journals Numerical Study on an Interface Compression Method for the Volume of Fluid Approach

Fluids ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 80
Author(s):  
Yuria Okagaki ◽  
Taisuke Yonomoto ◽  
Masahiro Ishigaki ◽  
Yoshiyasu Hirose
Keyword(s):  
Linear Theory ◽  
Volume Fraction ◽  
Numerical Study ◽  
Volume Of Fluid ◽  
Interfacial Wave ◽  
Validation Process ◽  
Two Phase ◽  
Numerical Diffusion ◽  
Mesh Resolution ◽  
Water Reactors

Many thermohydraulic issues about the safety of light water reactors are related to complicated two-phase flow phenomena. In these phenomena, computational fluid dynamics (CFD) analysis using the volume of fluid (VOF) method causes numerical diffusion generated by the first-order upwind scheme used in the convection term of the volume fraction equation. Thus, in this study, we focused on an interface compression (IC) method for such a VOF approach; this technique prevents numerical diffusion issues and maintains boundedness and conservation with negative diffusion. First, on a sufficiently high mesh resolution and without the IC method, the validation process was considered by comparing the amplitude growth of the interfacial wave between a two-dimensional gas sheet and a quiescent liquid using the linear theory. The disturbance growth rates were consistent with the linear theory, and the validation process was considered appropriate. Then, this validation process confirmed the effects of the IC method on numerical diffusion, and we derived the optimum value of the IC coefficient, which is the parameter that controls the numerical diffusion.

scholarly journals Numerical simulation of the motion of a micropolar Casson fluid through a porous medium over a stretching surface

2020 ◽  
Vol 24 (2 Part B) ◽  
pp. 1285-1297 ◽  
Author(s):  
Nabil El-Dabe ◽  
Galal Moatimid ◽  
Abd-Elhafez Elshekhipy ◽  
Naglaa Aballah
Keyword(s):  
Porous Medium ◽  
Casson Fluid ◽  
Similarity Solutions ◽  
Physical Parameters ◽  
Stretching Surface ◽  
Transform Method ◽  
Differential Transform ◽  
Non Linear ◽  
Linear Differential ◽  
External Uniform Magnetic Field

The present study examines the motion of a micropolar non-Newtonian Casson fluid through a porous medium over a stretching surface. The system is pervaded by an external uniform magnetic field. The heat transfer and heat generation are taken into consideration. The problem is modulated mathematically by a system of non-linear PDE which describe the equations of continuity, momentum, and energy. Suitable similarity solutions are utilized to transform the system of equation ordinary non-linear differential equations. In accordance with the appropriate boundary conditions, are numerically solved by means of the finite difference technique. Also, the system is solved by using multistep differential transform method. The effects of the various physical parameters, of the problem at hand, are illustrated through a set of diagrams.

Implementation of DTM as a numerical study for the Casson fluid flow past an exponentially variable stretching sheet with thermal radiation

2021 ◽  
pp. 2150111
Author(s):  
Khadijah M. Abualnaja
Keyword(s):  
Fluid Flow ◽  
Thermal Radiation ◽  
Numerical Method ◽  
Stretching Sheet ◽  
Numerical Solutions ◽  
Numerical Study ◽  
Transformation Method ◽  
Casson Fluid ◽  
Physical Parameters ◽  
Special Cases

This paper introduces a theoretical and numerical study for the problem of Casson fluid flow and heat transfer over an exponentially variable stretching sheet. Our contribution in this work can be observed in the presence of thermal radiation and the assumption of dependence of the fluid thermal conductivity on the heat. This physical problem is governed by a system of ordinary differential equations (ODEs), which is solved numerically by using the differential transformation method (DTM). This numerical method enables us to plot figures of the velocity and temperature distribution through the boundary layer region for different physical parameters. Apart from numerical solutions with the DTM, solutions to our proposed problem are also connected with studying the skin-friction coefficient. Estimates for the local Nusselt number are studied as well. The comparison of our numerical method with previously published results on similar special cases shows excellent agreement.

Numerical Study of Natural Convection in Vertical Cylindrical Annular Enclosure Filled with Cu-Water Nanofluid under Magnetic Fields

2019 ◽  
Vol 392 ◽  
pp. 123-137 ◽  
Author(s):  
Mohamed A. Medebber ◽  
Abderrahmane Aissa ◽  
Mohamed El Amine Slimani ◽  
Noureddine Retiel
Keyword(s):  
Natural Convection ◽  
Magnetic Fields ◽  
Volume Fraction ◽  
Numerical Study ◽  
Physical Parameters ◽  
Cold Temperatures ◽  
Simpler Algorithm ◽  
Wide Range ◽  
Nanoparticles Volume Fraction ◽  
Volume Method

The two dimensional study of natural convection in vertical cylindrical annular enclosure filled with Cu-water nanofluid under magnetic fields is numerically analyzed. The vertical walls are maintained at different uniform hot and cold temperatures, THand TC, respectively. The top and bottom walls of the enclosure are thermally insulated. The governing equations are solved numerically by using a finite volume method. The coupling between the continuity and momentum equations is effected using the SIMPLER algorithm. Numerical analysis has been carried out for a wide range of Rayleigh number (103≤Ra≤106), Hartmann number (1 ≤Ha≤100) and nanoparticles volume fraction (0 ≤φ≤0.08). The influence of theses physical parameters on the streamlines, isotherms and average Nusselt has been numerically investigated.

Numerical Simulation of Black Liquor Spray Characteristics

2002 ◽  
Author(s):  
Thomas D. Foust ◽  
Kurt D. Hamman ◽  
Brent A. Detering
Keyword(s):  
Droplet Size ◽  
Volume Fraction ◽  
Numerical Study ◽  
Black Liquor ◽  
Flow Distribution ◽  
Physical Models ◽  
Spray Characteristics ◽  
Two Phase ◽  
Vof Model ◽  
Sheet Breakup

The performance and capacity of Kraft recovery boilers is sensitive to black liquor velocity, droplet size and flow distribution in the furnace. Studies have shown that controlling droplet size and flow distribution improves boiler efficiency while allowing increased flight drying and devolatilization, and decreased carryover. The purpose of this study is to develop a robust two-phase numerical model to predict black liquor splashplate nozzle spray characteristics. A three-dimensional time dependent numerical study of black liquor sheet formation and sheet breakup is described. The volume of fluid (VOF) model is used to simulate flow through the splashplate nozzle up to initial sheet breakup and droplet formation. The VOF model solves the conservation equations of volume fraction and momentum utilizing the finite volume technique. Black liquor velocity, droplet size and flow distribution over a range of operating parameters are simulated using scaled physical models of splashplate nozzles. The VOF model is compared to results from a flow visualization experiment and experimental data found in the literature. The details of the simulation and experimental results are presented.

scholarly journals UNSTEADY BOUNDARY LAYERS: CONVECTIVE HEAT TRANSFER OVER A VERTICAL FLAT PLATE

2009 ◽  
Vol 50 (4) ◽  
pp. 541-549 ◽  
Author(s):  
ROBERT A. VAN GORDER ◽  
K. VAJRAVELU
Keyword(s):  
Heat Transfer ◽  
Differential Equations ◽  
Numerical Solutions ◽  
Approximate Solutions ◽  
Shear Thinning ◽  
Momentum Equation ◽  
Physical Parameters ◽  
Flow And Heat Transfer ◽  
Special Cases ◽  
Layer Flow

AbstractIn this paper, we extend the results in the literature for boundary layer flow over a horizontal plate, by considering the buoyancy force term in the momentum equation. Using a similarity transformation, we transform the partial differential equations of the problem into coupled nonlinear ordinary differential equations. We first analyse several special cases dealing with the properties of the exact and approximate solutions. Then, for the general problem, we construct series solutions for arbitrary values of the physical parameters. Furthermore, we obtain numerical solutions for several sets of values of the parameters. The numerical results thus obtained are presented through graphs and tables and the effects of the physical parameters on the flow and heat transfer characteristics are discussed. The results obtained reveal many interesting behaviours that warrant further study of the equations related to non-Newtonian fluid phenomena, especially the shear-thinning phenomena. Shear thinning reduces the wall shear stress.

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