| Summary: | The various debates in fluid dynamics from different critics made it so clear that the
existence of nanoparticles in the fluids leads to raising the thermal conductivity of the
fluid itself and therefore enhances the heat transfer properties. Moreover, the convection
heat transfer behaviors that enhanced by nanoparticles in the fluids have been widely
reviewed in mechanical engineering and modern industrial fields. Many researchers
have studied the convection b undary layer flow of incompressible micropolar fluid.
However, there is still a lack of studies that examine the behaviours of a micropolar
nanofluid on a solid sphere and horizontal circular cylinder. In the present study, the
free and mixed convection boundary layer flow for micropolar nanofluid on a solid
sphere and horizontal circular cylinder has been considered. The governing dimensional
equations of the boundary layer are first transformed into non-dimensional equations
via non-dimensional variables. The non-dimensional equations are transformed into
partial differential equations using similarity transformation. Next, the transformed
nonlinear systems of equations are solved via an implicit finite difference scheme
known as the Keller-Box method and programmed via MATLAB software. Effects of
mixed convection, nanoparticle volume fraction and micropolar parameters on the
behaviors of micropolar nanofluid are observed. The numerical result shows that a rise
in nanoparticle volume fraction and rnicropolar parameters lead to increment in the local
wall temperature and the temperature profile. Besides, the values of local wall
temperature and temperature profile decrease when the values of mixed convection
parameter increase. Furthermore, when the value of mixed convection parameter is
positive, the behaviors of local skin friction, velocity, and angular velocity of the
nanoparticles are opposite to the negative mixed convection parameter. The result
concludes that the behaviors of micropolar nanofluid flow is significantly influenced by
mixed convection, nanoparticle volume fraction and micropolar parameters. Therefore,
this finding is expected to add a scientific insertion to the fluid mechanics field.
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