Mixed convection flow of viscoelastic nanofluid past a horizontal circular cylinder with viscous dissipation, heat generation and radiation
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Date
2020
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Universiti Teknologi Malaysia
Abstract
The conventional heat transfer fluids often face several limitations in heat transfer process and gives a lower heat transfer rate in thermal engineering systems which also affect the performance of the heat transfer processes in industries. Therefore, to overcome this problem, researchers have considered a new generation of heat transfer fluid, known as nanofluid with higher thermal conductivity. The concept of nanofluid refers to a new technology in heat transport fluid by mixing nanoparticles in a base fluid which can increase the heat transfer performance. Therefore, in this research a mathematical model of mixed convection flow of nanofluid was developed to study the influence of several effects on viscoelastic fluid with heat transfer. In particular, the flow of viscoelastic nanofluid passing through a horizontal circular cylinder with the effects of viscous dissipation, heat generation and radiation were investigated. The nanofluid in this research was considered based on Tiwari and Das model with the influence of two different boundary conditions which are convective boundary condition (CBC) and constant heat flux (CHF). The governing nonlinear equations in the form of partial differential equations were reduced into ordinary differential equations using appropriate similarity transformation and then were solved numerically using Keller box method. The numerical values of the skin friction coefficient, heat transfer coefficient which represents the heat transfer rate at the surface as well as the velocity and temperature profiles were obtained for mixed convection parameter, viscoelastic parameter, nanoparticles volume fraction, Biot number, Eckert number, heat generation parameter and radiation parameter. All results obtained displayed graphically and analysed in details. Numerical results showed that, the presence of nanoparticles in viscoelastic fluid with all types of effects enhance the temperature profiles and consequently increased the heat transfer coefficient. It is observed that, the highest velocity and temperature profiles were occurred when the effect of heat generations was applied for both cases, CBC and CHF. However, this effect created the lowest skin friction and heat transfer coefficients in the CHF case. Comparative results amongst two cases also showed that, CHF contributed the highest profile in all velocity and temperature fields, as well as skin friction and heat transfer coefficients. Whereas, with the combination of all temperature effects gave the highest value in skin friction and heat transfer coefficients for CBC case.
Description
Thesis (PhD. (Chemistry))
Keywords
Nanofluids, Heat--Transmission