Interaction of Al2O3-Ag and Al2O3-Cu hybrid nanoparticles with water on convectively heated moving material

2020 ◽  
Vol 16 (6) ◽  
pp. 1651-1667 ◽  
Author(s):  
G.K. Ramesh ◽  
G.S. Roopa ◽  
SabirAli Shehzad ◽  
S.U. Khan
Keyword(s):  
Nusselt Number ◽  
Skin Friction ◽  
Heat Transport ◽  
Ag Nanoparticles ◽  
Design Methodology ◽  
Pure Water ◽  
Hybrid Nanoparticles ◽  
Governing Equations ◽  
Numerical Illustration ◽  
Content Type

PurposeThe aim of present work is to study the flow and heat transport structures of hybrid nanoparticles in a moving material. Two types of hybrid nanoparticles have been chosen namely Al2O3-Cu and Al2O3-Ag nanoparticles (90%) within 10% of pure water.Design/methodology/approachLeading governing equations are transformed through similarity technique and then computed for numerical illustration by applying RKF method.FindingsThe author observed that the skin friction value of Al2O3-Cu/water case is lesser in comparison to the values of Nusselt number for Al2O3-Ag/water nanoparticles.Originality/valueThere exist no such study which addressed such phenomenon.

Nanofluid flow past an impulsively started vertical plate with variable surface temperature

2016 ◽  
Vol 26 (1) ◽  
pp. 328-347 ◽  
Author(s):  
Rajesh Vemula ◽  
A J Chamkha ◽  
Mallesh M. P.
Keyword(s):  
Nusselt Number ◽  
Friction Coefficient ◽  
Skin Friction ◽  
Vertical Plate ◽  
Aluminium Oxide ◽  
Skin Friction Coefficient ◽  
Viscous Drag ◽  
Content Type ◽  
Variable Surface ◽  
Variable Surface Temperature

Purpose – The purpose of this paper is to focus on the numerical modelling of transient natural convection flow of an incompressible viscous nanofluid past an impulsively started semi-infinite vertical plate with variable surface temperature. Design/methodology/approach – The problem is governed by the coupled non-linear partial differential equations with appropriate boundary conditions. A robust, well-tested, Crank-Nicolson type of implicit finite-difference method, which is unconditionally stable and convergent, is used to solve the governing non-linear set of partial differential equations. Findings – The local and average values of the skin-friction coefficient (viscous drag) and the average Nusselt number (the rate of heat transfer) decreased, while the local Nusselt number increased for all nanofluids, namely, aluminium oxide-water, copper-water, titanium oxide-water and silver-water with an increase in the temperature exponent m. Selecting aluminium oxide as the dispersing nanoparticles leads to the maximum average Nusselt number (the rate of heat transfer), while choosing silver as the dispersing nanoparticles leads to the minimum local Nusselt number compared to the other nanofluids for all values of the temperature exponent m. Also, choosing silver as the dispersing nanoparticles leads to the minimum skin-friction coefficient (viscous drag), while selecting aluminium oxide as the dispersing nanoparticles leads to the maximum skin-friction coefficient (viscous drag) for all values of the temperature exponent m. Research limitations/implications – The Brinkman model for dynamic viscosity and Maxwell-Garnett model for thermal conductivity are employed. The governing boundary layer equations are written according to The Tiwari-Das nanofluid model. A range of nanofluids containing nanoparticles of aluminium oxide, copper, titanium oxide and silver with nanoparticle volume fraction range less than or equal to 0.04 are considered. Practical implications – The present simulations are relevant to nanomaterials thermal flow processing in the chemical engineering and metallurgy industries. This study also provides an important benchmark for further simulations of nanofluid dynamic transport phenomena of relevance to materials processing, with alternative computational algorithms (e.g. finite element methods). Originality/value – This paper is relatively original and illustrates the influence of variable surface temperature on transient natural convection flow of a viscous incompressible nanofluid and heat transfer from an impulsively started semi-infinite vertical plate.

Hybrid nanofluid flow and heat transfer over a nonlinear permeable stretching/shrinking surface

2019 ◽  
Vol 29 (9) ◽  
pp. 3110-3127 ◽  
Author(s):  
Iskandar Waini ◽  
Anuar Ishak ◽  
Ioan Pop
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Friction Coefficient ◽  
Skin Friction ◽  
Local Nusselt Number ◽  
Skin Friction Coefficient ◽  
Hybrid Nanofluid ◽  
Content Type ◽  
Flow And Heat Transfer ◽  
Shrinking Surface

PurposeThis paper aims to investigate the steady flow and heat transfer of a Cu-Al2O3/water hybrid nanofluid over a nonlinear permeable stretching/shrinking surface with radiation effects. The surface velocity condition is assumed to be of the power-law form with an exponent of 1/3. The governing equations of the problem are converted into a system of similarity equations by using a similarity transformation.Design/methodology/approachThe problem is solved numerically using the boundary value problem solver (bvp4c) in Matlab software. The results of the skin friction coefficient and the local Nusselt number as well as the velocity and temperature profiles are presented through graphs and tables for several values of the parameters. The effects of these parameters on the flow and heat transfer characteristics are examined and discussed.FindingsResults found that dual solutions exist for a certain range of the stretching/shrinking and suction parameters. The increment of the skin friction coefficient and reduction of the local Nusselt number on the shrinking sheet is observed with the increasing of copper (Cu) nanoparticle volume fractions for the upper branch. The skin friction coefficient and the local Nusselt number increase when suction parameter is increased for the upper branch. Meanwhile, the temperature increases in the presence of the radiation parameter for both branches.Originality/valueThe problem of Cu-Al2O3/water hybrid nanofluid flow and heat transfer over a nonlinear permeable stretching/shrinking surface with radiation effects is the important originality of the present study where the dual solutions for the flow reversals are obtained.

Free convection in a square porous cavity filled with a nanofluid using thermal non equilibrium and Buongiorno models

2016 ◽  
Vol 26 (3/4) ◽  
pp. 671-693 ◽  
Author(s):  
Ioan Pop ◽  
Mohammad Ghalambaz ◽  
Mikhail Sheremet
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Brownian Motion ◽  
Base Fluid ◽  
Average Nusselt Number ◽  
Solid Phase ◽  
Porous Matrix ◽  
Governing Equations ◽  
Content Type ◽  
Brownian Motion And Thermophoresis

Purpose – The purpose of this paper is to theoretically analysis the steady-state natural convection flow and heat transfer of nanofluids in a square enclosure filled with a porous medium saturated with a nanofluid considering local thermal non-equilibrium (LTNE) effects. Different local temperatures for the solid phase of the nanoparticles, the solid phase of porous matrix and the liquid phase of the base fluid are taken into account. Design/methodology/approach – The Buongiorno’s model, incorporating the Brownian motion and thermophoresis effects, is utilized to take into account the migration of nanoparticles. Using appropriate non-dimensional variables, the governing equations are transformed into the non-dimensional form, and the finite element method is utilized to solve the governing equations. Findings – The results show that the increase of buoyancy ratio parameter (Nr) decreases the magnitude of average Nusselt number. The increase of the nanoparticles-fluid interface heat transfer parameter (Nhp) increases the average Nusselt number for nanoparticles and decreases the average Nusselt number for the base fluid. The nanofluid and porous matrix with large values of modified thermal capacity ratios (γ p and γ s ) are of interest for heat transfer applications. Originality/value – The three phases of nanoparticles, base fluid and the porous matrix are in the LTNE. The effect of mass transfer of nanoparticles due to the Brownian motion and thermophoresis effects are also taken into account.

Natural convection flow in a vertical micro-annulus with time-periodic thermal boundary conditions

2018 ◽  
Vol 14 (5) ◽  
pp. 1064-1081
Author(s):  
Basant Kumar Jha ◽  
Michael O. Oni
Keyword(s):  
Nusselt Number ◽  
Natural Convection ◽  
Boundary Conditions ◽  
Skin Friction ◽  
Convection Flow ◽  
Natural Convection Flow ◽  
Content Type ◽  
Thermal Boundary Conditions ◽  
The Impact ◽  
Time Periodic

PurposeThe purpose of this paper is to investigate the impact of time-periodic thermal boundary conditions on natural convection flow in a vertical micro-annulus.Design/methodology/approachAnalytical solution in terms of Bessel’s function and modified Bessel’s function of order 0 and 1 is obtained for velocity, temperature, Nusselt number, skin friction and mass flow rate.FindingsIt is established that the role of Knudsen number and fluid–wall interaction parameter is to decrease fluid temperature, velocity, Nusselt number and skin friction.Research limitations/implicationsNo laboratory practical or experiment was conducted.Practical implicationsCooling device in electronic panels, card and micro-chips is frequently cooled by natural convection.Originality/valueIn view of the amount of works done on natural convection in microchannel, it becomes interesting to investigate the effect that time-periodic heating has on natural convection flow in a vertical micro-annulus. The purpose of this paper is to examine the impact of time-periodic thermal boundary conditions on natural convection flow in a vertical micro-annulus.

Three weighted residual methods based on Jeffery-Hamel flow

2014 ◽  
Vol 24 (3) ◽  
pp. 654-668 ◽  
Author(s):  
D.D. Ganji ◽  
Mohammad Hatami
Keyword(s):  
Analytical Methods ◽  
Design Methodology ◽  
Least Square Method ◽  
Numerical Approach ◽  
Least Square ◽  
The Other ◽  
Governing Equations ◽  
Science And Engineering ◽  
Content Type ◽  
Linear Differential

Purpose – The purpose of this paper is to demonstrate the eligibility of the weighted residual methods (WRMs) applied to Jeffery-Hamel Flow. Selecting the most appropriate method among the WRMs and discussing about Jeffery-Hamel flow's treatment in divergent and convergent channels are the other important purposes of the present research. Design/methodology/approach – Three analytical methods (collocation, Galerkin and least square method) have been applied to solve the governing equations. The reliability of the methods is also approved by a comparison made between the forth order Runge-Kutta numerical method. Findings – The obtained solutions revealed that WRMs can be simple, powerful and efficient techniques for finding analytical solutions in science and engineering non-linear differential equations. Originality/value – It could be considered as a first endeavor to use the solution of the Jeffery-Hamel flow using these kind of analytical methods along with the numerical approach.

Characterization of lubrication of asymmetric rollers including thermal effects

2015 ◽  
Vol 67 (3) ◽  
pp. 246-255
Author(s):  
Venkata Subrahmanyam Sajja ◽  
Dhaneshwar Prasad
Keyword(s):  
Power Law ◽  
Thermal Effects ◽  
Design Methodology ◽  
Hydrodynamic Lubrication ◽  
Flow Equation ◽  
Theoretical Problem ◽  
Governing Equations ◽  
Content Type ◽  
The Mean

Purpose – The purpose of this paper is to deal with the qualitative analysis of hydrodynamic lubrication of asymmetric rollers with non-Newtonian incompressible power law lubricants including Newtonian. Design/methodology/approach – The fluid flow governing equations such as equation of motion along with continuity and thermal equations are solved first analytically and investigated numerically by the Runge-Kutta Fehlberg method. Findings – As a result of this work, it is found that there is a significant change in temperature, pressure, load and traction with Newtonian and non-Newtonian fluids. Research limitations/implications – The authors considered incompressible hydrodynamic lubrication of two rigid asymmetric rollers, one of them is assumed to be adiabatic. The convection term of the heat flow equation is taken in its average form. Originality/value – It is a theoretical problem of two heavily loaded rigid cylindrical rollers with cavitations, where the consistency of the power law lubricant is assumed to vary with pressure and the mean film temperature. It has not appeared in the literature.

Thermally stratified stagnation point flow of Casson fluid with slip conditions

2015 ◽  
Vol 25 (4) ◽  
pp. 724-748 ◽  
Author(s):  
Tasawar Hayat ◽  
Muhammad Farooq ◽  
A. Alsaedi
Keyword(s):  
Velocity Profile ◽  
Stagnation Point ◽  
Design Methodology ◽  
Casson Fluid ◽  
Series Solutions ◽  
Analysis Method ◽  
Governing Equations ◽  
Content Type ◽  
Slip Effects ◽  
Homotopy Analysis

Purpose – The purpose of this paper is to focus on the stratified phenomenon through vertical stretching cylinder in the region of stagnation point with slip effects. Design/methodology/approach – Homotopy analysis method is used to find the series solutions of the governing equations. Findings – Velocity profile decreases with an increase in stratified parameters due to temperature and concentration. Velocity and thermal slips cause a reduction in the velocity profile. Thermally stratified and thermal slip parameters reduce the temperature field. Originality/value – The present analysis has not been existed in the literature yet.

An analytical approach for analysis and optimization of formation of field-effect heterotransistors

2016 ◽  
Vol 12 (4) ◽  
pp. 578-604 ◽  
Author(s):  
Evgeny L. Pankratov ◽  
Elena A. Bulaeva
Keyword(s):  
Heat Transport ◽  
Technological Process ◽  
Multilayer Structure ◽  
Field Effect ◽  
Design Methodology ◽  
Analytical Approach ◽  
Charge Carriers ◽  
Cross Linking ◽  
Content Type ◽  
Time Parameters

Purpose The purpose of this paper is to analyze and optimize the formation of field-effect heterotransistors using analytical approach. The approach makes it possible to analyze mass and heat transport in a multilayer structure without cross-linking of solutions on interfaces between layers of the multilayer structure. The optimization makes it possible to decrease dimensions of the heterotransistors and to increase speed of transport of charge carriers during functioning of the transistors. Design/methodology/approach The authors introduce an analytical approach for analysis of mass and heat transport, which makes it possible to take into account at one time varying in space and time parameters of the transports (diffusion coefficient, heat conduction coefficient, etc.) and nonlinearity of processes. The approach enables analysis of mass and heat transport in a multilayer structure without cross-linking of solutions on interfaces between layers of the multilayer structure and optimises the technological process. The optimization means it is possible to decrease dimensions of field-effect heterotransistors. Findings In this paper the authors introduce an approach to manufacture a field-effect heterotransistor with inhomogeneous doping of channel. Some recommendations to optimize technological process to manufacture more compact distribution of concentration of dopant have been formulated. Originality/value The results are original and the paper provides an approach to the manufacture of a field-effect heterotransistor.

scholarly journals Numerical simulation of NACA4412 airfoil in pre-stall conditions

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Vincent Gleize ◽  
Michel Costes ◽  
Ivan Mary
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Mach Number ◽  
Skin Friction ◽  
Flow Separation ◽  
Turbulent Mixing ◽  
Design Methodology ◽  
Freestream Velocity ◽  
Content Type ◽  
Laminar Separation

Purpose The purpose of this paper is to study turbulent flow separation at the airfoil trailing edge. This work aims to improve the knowledge of stall phenomenon by creating a QDNS database for the NACA412 airfoil. Design/methodology/approach Quasi-DNS simulations of the NACA 4412 airfoil in pre-stall conditions have been completed. The Reynolds number based on airfoil chord and freestream velocity is equal to 0.35 million, and the freestream Mach number to 0.117. Transition is triggered on both surfaces for avoiding the occurrence of laminar separation bubbles and to ensure turbulent mixing in the wake. Four incidences have been considered, 5, 8 10 and 11 degrees. Findings The results obtained show a reasonably good correlation of the present simulations with classical MSES airfoil simulations and with RANS computations, both in terms of pressure and skin-friction distribution, with an earlier and more extended flow separation in the QDNS. The database thus generated will be deeply analysed and enriched for larger incidences in the future. Originality/value No experimental or HPC numerical database at reasonable Reynolds number exists in the literature. The current work is the first step in that direction.

Brinkman-Forchheimer flow of SWCNT and MWCNT magneto-nanoliquids in a microchannel with multiple slips and Joule heating aspects

2018 ◽  
Vol 14 (4) ◽  
pp. 769-786 ◽  
Author(s):  
Shashikumar N.S. ◽  
Gireesha B.J. ◽  
B. Mahanthesh ◽  
Prasannakumara B.C.
Keyword(s):  
Carbon Nanotubes ◽  
Nusselt Number ◽  
Joule Heating ◽  
Microchannel Flow ◽  
Governing Equations ◽  
Content Type ◽  
Swcnts And Mwcnts ◽  
Walled Carbon Nanotubes ◽  
Multiple Slips ◽  
Forchheimer Flow

Purpose The microfluidics has a wide range of applications, such as micro heat exchanger, micropumps, micromixers, cooling systems for microelectronic devices, fuel cells and microturbines. However, the enhancement of thermal energy is one of the challenges in these applications. Therefore, the purpose of this paper is to enhance heat transfer in a microchannel flow by utilizing carbon nanotubes (CNTs). MHD Brinkman-Forchheimer flow in a planar microchannel with multiple slips is considered. Aspects of viscous and Joule heating are also deployed. The consequences are presented in two different carbon nanofluids. Design/methodology/approach The governing equations are modeled with the help of conservation equations of flow and energy under the steady-state situation. The governing equations are non-dimensionalized through dimensionless variables. The dimensionless expressions are treated via Runge-Kutta-Fehlberg-based shooting scheme. Pertinent results of velocity, skin friction coefficient, temperature and Nusselt number for assorted values of physical parameters are comprehensively discussed. Also, a closed-form solution is obtained for momentum equation for a particular case. Numerical results agree perfectly with the analytical results. Findings It is established that multiple slip effect is favorable for velocity and temperature fields. The velocity field of multi-walled carbon nanotubes (MWCNTs) nanofluid is lower than single-walled carbon nanotubes (SWCNTs)-nanofluid, while thermal field, Nusselt number and drag force are higher in the case of MWCNT-nanofluid than SWCNT-nanofluid. The impact of nanotubes (SWCNTs and MWCNTs) is constructive for thermal boundary layer growth. Practical implications This study may provide useful information to improve the thermal management of microelectromechanical systems. Originality/value The effects of CNTs in microchannel flow by utilizing viscous dissipation and Joule heating are first time investigated. The results for SWCNTs and MWCNTs have been compared.

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