2 research outputs found
Convective heat and mass transfer in boundary layer flow through porous media saturated with nanofluids.
Doctor of Philosophy in Mathematics. University of KwaZulu-Natal, Pietermaritzburg 2016.The thesis is devoted to the study of flow, heat and mass transfer processes, and crossdiffusion
effects in convective boundary layer flows through porous media saturated with
nanofluids. Of particular interest is how nanofluids perform as heat transfer fluids compared
to traditional fluids such as oil and water. Flow in different geometries and subject to
various source terms is investigated.
An important aspect of the study and understanding of transport processes is the solution of
the highly non-linear coupled differential equations that model both the flow and the heat
transportation. In the literature, various analytical and numerical methods are available for
finding solutions to fluid flow equations. However, not all these methods give accurate
solutions, are stable, or are computationally efficient. For these reasons, it is important to
constantly devise numerical schemes that work more efficiently, including improving the
performance of existing schemes, to achieve accuracy with less computational effort. In this
thesis the systems of differential equations that describe the fluid flow and other transport
processes were solved numerically using both established and recent numerical schemes
such as the spectral relaxation method and the spectral quasilinearization method. These
spectral methods have been used only in a limited number of studies. There is therefore the
need to test and prove the accuracy and general application of the methods in a wider class
of boundary value problems.
The accuracy, convergence, and validity of the solutions obtained using spectral methods,
have been established by careful comparison with solutions for limiting cases in the published
literature, or by use of a different solution method.
In terms of understanding the physically important variables that impact the flow, we have
inter alia, investigated the significance of different fluid and physical parameters, and how
changes in these parameters affect the skin friction coefficient, the heat and mass transfer
rates and the fluid properties. Some system parameters of interest in this study include the
nanoparticle volume fraction, the Hartmann number, thermal radiation, Brownian motion,
the heat generation, the Soret and Dufour effects, and the Prandtl and Schmidt number. The
dependency of the heat, mass transfer and skin friction coefficients on these parameters has
been quantified and discussed.
In this thesis, we show that nanofluids have a significant impact on heat and mass transfer
processes compared with traditional heat transfer fluids
Double-diffusive convection flow in a porous medium saturated with a nanofluid.
In this work, we studied heat and mass transfer in a nanofluid flow over a stretching sheet.
Fluid flow in different flow geometries was studied and a co-ordinate transformation was
used to transform the governing equations into non-dimensional non-similar boundary layer
equations. These equations were then solved numerically using both established and recent
techniques such as the spectral relaxation and spectral quasi-linearization methods. Numerical
solutions for the heat transfer, mass transfer and skin friction coefficients have been presented
for different system parameters, such as heat generation, Soret and Dufour effects, chemical
reaction, thermal radiation influence, the local Grashof number, Prandtl number, Eckert number,
Hartmann number and the Schmidt number. The dependency of the skin friction, heat
and mass transfer coefficients on these parameters has been quantified and discussed. The
accuracy, and validity of the spectral relaxation and spectral quasi-linearization methods has
been established