  Direct numerical simulations of turbulent convection at high Rayleigh numbers
in large aspect ratio cells are challenging because of the prohibitive
computational resources required. One can achieve high Rayleigh numbers at
affordable costs for low aspect ratios, but the effect of small aspect ratio
remains to be understood fully. In this work, we explore integral quantities in
convection in a cell with the small aspect ratio of 0.1 by varying both the
Rayleigh and Prandtl numbers systematically. We find that the heat transport in
this flow is within 10\% of that in cells with large aspect ratios for high
enough Rayleigh numbers and for Prandtl numbers larger than unity. For low
Prandtl numbers, the increase of the heat transport is steeper for low aspect
ratios, approaching that in large aspect ratios as the Prandtl number
increases. Further, the global momentum transport, quantified by the Reynolds
number, is reduced for all Prandtl numbers, presumably because of the larger
volume of flow affected by the friction from sidewalls, compared to that in
cells of larger aspect ratio.
