  An experimental and numerical smoothed particle hydrodynamics (SPH) analysis
was performed for the convective flow arising from a horizontal, thin
cylindrical heat source enclosed in a glycerin-filled, slender enclosure at low
Rayleigh numbers ($1.18\leq {\rm Ra}\leq 242$). Both the experiments and the
SPH calculations were performed for positive ($0.1\leq\Delta T\leq 10$ K) and
negative ($-10\leq\Delta T\leq -0.1$ K) temperature differences between the
source and the surrounding fluid. In all cases a pair of steady,
counter-rotating vortices is formed, accompanied by a plume of vertically
ascending flow just above the source for $\Delta T>0$ and a vertically
descending flow just below the source for $\Delta T<0$. The maximum flow
velocities always occur within the ascending/descending plumes. The SPH
predictions are found to match the experimental observations acceptably well
with root-mean-square errors in the velocity profiles of the order of $\sim
10^{-5}$ m s$^{-1}$. The fact that the SPH method is able to reveal the
detailed features of the flow phenomenon demonstrates the correctness of the
approach.
