2 research outputs found
Numerical studies of nanofluid boundary layer flows using spectral methods.
Doctoral Degree. University of KwaZulu-Natal, PietermaritzburgThis thesis is focused on numerical studies of heat and mass transport processes that occur in
nanofluid boundary layer flows. We investigate heat and mass transfer mechanisms in the flow of
a micropolar nanofluid above a stretching sheet, the squeezed nanofluid flow between two parallel
plates and the impact of activation energy and binary chemical reaction on nanofluid flow past
a rotating disk. We present an analysis of entropy generation in nanofluid flow past a rotating
disk and nanofluid flow past a stretching surface under the influence of an inclined magnetic field.
This study aims to numerically determine to a high degree of accuracy, how nanoparticles can
be utilized to alter heat and transport properties of base fluids in order to enhance or achieve
desirable properties for thermal systems. The heat and mass transfer processes that feature in
nanofluid boundary layer flow are described by complex nonlinear transport equations which are
difficult to solve. Because of the complex nature of the constitutive equations describing the flow
of nanofluids, finding analytic solutions has often proved intractable.
In this study, the model equations are solved using the spectral quasilinearization method. This
method is relatively recent and has not been adequately utilized by researchers in solving related
problems. The accuracy and reliability of the method are tested through convergence error and
residual error analyses. The accuracy is further tested through a comparison of results for limiting
cases with those in the literature. The results confirm the spectral quasilinearization method as
being accurate, efficient, rapidly convergent and suited for solving boundary value problems. In
addition, among other findings, we show that nanofluid concentration enhances heat and mass
transfer rates while the magnetic field reduces the velocity distribution. The fluid flows considered
in this study have significant applications in science, engineering and technology. The findings
will contribute to expanding the existing knowledge on nanofluid flow
A numerical study of heat and mass transfer in non-Newtonian nanofluid models.
Doctoral Degree. University of KwaZulu-Natal, Pietermaritzburg.A theoretical study of boundary layer flow, heat and mass transport in non-Newtonian
nanofluids is presented. Because of the diversity in the physical structure and properties of
non-Newtonian fluids, it is not possible to describe their behaviour using a single constitutive
model. In the literature, several constitutive models have been proposed to predict the behaviour
and rheological properties of non-Newtonian fluids. The question of interest is how
the fluid physical parameters affect the boundary layer flow, and heat and mass transfer in
various nanofluids.
In this thesis, nanofluid models in various geometries and subject to different boundary
conditions are constructed and analyzed. A range of fluid models from simple to complex
are studied, leading to highly nonlinear and coupled differential equations, which require
advanced numerical methods for their solution.
This thesis is a conjoin between mathematical modeling of non-Newtonian nanofluid flows
and numerical methods for solving differential equations. Some recent spectral techniques
for finding numerical solutions of nonlinear systems of differential equations that model fluid
flow problems are used. The numerical methods of primary interest are spectral quasilinearization,
local linearization and bivariate local linearization methods. Consequently, one of
the objectives of this thesis is to test the accuracy, robustness and general validity of these
methods.
The dependency of heat and mass transfer, and skin friction coefficients on the physical
parameters is quantified and discussed. Results show that nanofluids and physical parameters
have an important and significant impact on boundary layer flows, and on heat and mass
transfer processes.The year on the title page reflects as 2019 on the thesis and differs from that on pages ii to iv which indicates the year 2020