The effect of gravity on the rate of a simple liquid-state reaction in a small, unstirred cylindrical vessel

The volume-averaged rate of a simple, liquid-state isomerisation reaction, initially at room temperature, inside an upright cylindrical container with a perfectly thermally conducting sidewall maintained at a constant elevated temperature has been followed theoretically, both in the presence and in the absence of gravity. Computational fluid dynamics modelling, using the finite-volume method, indicates that the net reaction progresses much faster in the presence of gravity. This accelerated rate of product formation is attributed to the effects of thermal convection currents, which cause more rapid heat transfer to the reaction vessel and are absent under conditions of zero gravity. The influence of natural convection on the spatial patterns of species concentration and of temperature is also illustrated in this article.