Abstract:
The present dissCl1alion deals with the problem of laminar natural convection
around a horizontal cylinder. The external surface of tlllS cylinder IS
everywhere isothermal, with the exception of a region, which is adiabatic. The
effects Ofvcl1ical cold walls arc also determined.
The basic boundary layer equations have been reduced to local Ilonsimilarity
equations. Solutions arc obtained employing the perturbation method together
with the Runge-Kulla imtml value problem solver, the mtcgral solution
method and the finite volume method incorporating the SIMPLE algorithm Oll
collocated body fitted grids.
Perturbation as well as [mite volume solutions are obtained, respectively, for
!lIe leading edge and for the entire regimes. The results obtained are presented
in terms of local heat transfer, streamlines, isothemlallines, velocity vectors,
velOCItymid temperature profiles.
On analysing the heat transfer from the cylinder, it has been found that the
intensity decreased and increased lmexpectedly. The.explanation can be given
after visualization of flow. 11is ohserved that the fluid near the vertical walls
aspirated the layers of hot fluid from the honzontal cylinder. The uplift
pressure and the tendency of the system to reach balance cause the thud layers
of the similar temperature and density to merge. However, this efTect also
found to be dependent on the intensity of the heat transfer.
Effects of the aforementioned physical quantities for fluid having differenl
Grashof number and Prandtl number have been studied. The effects of thc
cold wall and adiabatic part of the cylinder on the flow and thermal fields have
also been studied.
