Flow and Heat Transfer of Nanofluids near a Rotating Disk

2013 ◽  
Vol 664 ◽  
pp. 859-865
Author(s):  
I Chung Liu ◽  
Hung Hsun Wang ◽  
Chia Nan Liu

The study of boundary layer flow and heat transfer near a rotating disk with nanofluids is investigated numerically. Three types of nanoparticles, namely, silver Ag, copper Cu and alumina Al2O3with water as the base fluid are considered. The results show that the momentum boundary layer thicknesses shortens as the nanoparticle volume fraction increases, whereas thermal boundary layer thickness elongates for increasing ϕ. It is found that the reduced skin-friction coefficients and heat transfer rateat the rotating surface increase linearly with nanoparticle volume fractionϕ. The surface heat transfer rate for Cu-water nanofluid is higher than those of the otherswhen ϕ>0.02, even though the nanoparticle Ag has higher thermal conductivity than that of copper Cu.

Author(s):  
A. D. Gosman ◽  
M. L. Koosinlin ◽  
F. C. Lockwood ◽  
D. B. Spalding

A calculation procedure has been developed for predicting fluid-flow and heat-transfer phenomena in axisymmetrical, rotating, turbulent, steady flows, with special reference to those mainly confined within cavities. The procedure has been used for predicting boundary-layer flow between a rotating disk and a stationary one, and flow and heat transfer in a shrouded-disk system. Agreement with experimental measurements is satisfactory.


Author(s):  
Radu Trimbitas ◽  
Teodor Grosan ◽  
Ioan Pop

Purpose – The purpose of this paper is to theoretically study the problem of mixed convection boundary layer flow and heat transfer past a vertical needle with variable wall temperature using nanofluids. The similarity equations are solved numerically for copper nanoparticles in the based fluid of water to investigate the effect of the solid volume fraction parameter of the fluid and heat transfer characteristics. The skin friction coefficient, Nusselt number, and the velocity and temperature profiles and are graphically presented and discussed. Design/methodology/approach – The transformed system of ordinary differential equations was solved using the function bvp4c from Matlab. The relative tolerance was set to 1e-10. For the study of the stability the authors also used the bvp4c function in combination with chebfun package from Matlab. Findings – It is found that the solid volume fraction affects the fluid flow and heat transfer characteristics. The numerical results for a regular fluid and forced convection flow are compared with the corresponding results reported by Chen and Smith. The solutions exists up to a critical value of λ, beyond which the boundary layer separates from the surface and the solution based upon the boundary-layer approximations is not possible Originality/value – The paper describes how multiple (dual) solutions for the flow reversals are obtained. A stability analysis for this flow reversal has been also done showing that the lower solution branches are unstable, while the upper solution branches are stable.


2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Norihan Md. Arifin ◽  
Roslinda Nazar ◽  
Ioan Pop

The problem of steady Marangoni boundary layer flow and heat transfer over a flat plate in a nanofluid is studied using different types of nanoparticles. The general governing partial differential equations are transformed into a set of two nonlinear ordinary differential equations using unique similarity transformation. Numerical solutions of the similarity equations are obtained using the Runge-Kutta-Fehlberg (RKF) method. Three different types of nanoparticles are considered, namely, Cu, Al2O3, and TiO2, by using water as a base fluid with Prandtl numberPr=6.2. The effects of the nanoparticle volume fractionϕand the constant exponentmon the flow and heat transfer characteristics are obtained and discussed.


2021 ◽  
Vol 10 (1) ◽  
pp. 106-117
Author(s):  
Vishwanath B. Awati ◽  
N. Mahesh Kumar

The paper presents, the steady state two-dimensional forced convection boundary layer flow of heat transfer past a semi-infinite static flat plate (Blasius problem) and moving flat plate (Sakiadis problem) in the water based nanofluid with various nanoparticles. The self-similar solution exists for the boundary layer equations and using suitable similarity variables, the governing equations have been converted into coupled nonlinear ordinary differential equations (NODEs) with an infinite domain. The governing problems over an infinite interval were solved using semi-numerical technique which makes the use of power of Haar wavelets coupled with collocation method. The solutions obtained using wavelet methods have been confirmed to be more accurate as compared to other previously published results. The several physical interesting results of the problem are concentrated and verified through numerical schemes. Three different types of nonmetallic or metallic nanoparticles such as alumina (Al2O3), copper (Cu) and titania (TiO2) in the base fluid of water with Prandtl number Pr = 6.2, to study the effect of solid volume fraction parameter Φ of the nanofluids. The effect of local skin friction coefficients, Nusselt number, velocity and temperature profiles are plotted for various values of nanoparticle volume fractions and for different nanoparticles are analyzed in detail, the numerical results are presented in terms of Tables. It predicts that, the solid volume fraction affects the fluid flow and heat transfer characteristics.


2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Rahimah Jusoh ◽  
Roslinda Nazar ◽  
Ioan Pop

The problem of boundary layer flow and heat transfer of magnetohydrodynamic (MHD) nanofluids which consist of Fe3O4, Cu, Al2O3, and TiO2 nanoparticles and water as the base fluid past a bidirectional exponentially permeable stretching/shrinking sheet is studied numerically. The mathematical model of the nanofluid incorporates the effect of viscous dissipation in the energy equation. By employing a suitable similarity transformation, the conservative equations for mass, momentum, and energy are transformed into the ordinary differential equations. These equations are then numerically solved with the utilization of bvp4c function in matlab. The effects of the suction parameter, magnetic parameter, nanoparticle volume fraction parameter, Eckert number, Prandtl number, and temperature exponent parameter to the reduced skin friction coefficient as well as the local Nusselt number are graphically presented. Cu is found to be prominently good in the thermal conductivity. Nevertheless, higher concentration of nanoparticles leads to the deterioration of heat transfer rate. The present result negates the previous literature on thermal conductivity enhancement with the implementation of nanofluid. Stability analysis is conducted since dual solutions exist in this study, and conclusively, the first solution is found to be stable.


2011 ◽  
Vol 133 (5) ◽  
Author(s):  
T. Grosan ◽  
I. Pop

The classical problem of forced convection boundary layer flow and heat transfer past a needle with variable wall temperature using nanofluids is theoretically studied. The similarity equations are solved numerically for two types of metallic or nonmetallic, such as copper (Cu) and alumina (Al2O3) nanoparticles in the based fluid of water with the Prandtl number Pr=7 to investigate the effect of the solid volume fraction parameter ϕ of the fluid and heat transfer characteristics. The skin friction coefficient, Nusselt number, and the velocity and temperature profiles are presented and discussed. It is found that the solid volume fraction affects the fluid flow and heat transfer characteristics.


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