Natural convective oscillatory flow in cylindrical annuli

Abstract Detailed quantitative information is presented concerning the characteristics of a natural convective oscillatory flow in horizontal, cylindrical annuli. This unusual, three-dimensional oscillatory flow is described by giving amplitude, period, and wave length data as well as data showing when this type of flow has its inception from a previously stable flow at lower Grashof numbers. Visualization of the air flow was achieved by the use of tobacco smoke. Annulus pressure was varied from 13.8 to 275.8 kN/m 2 while the temperature difference between the cylinders was varied from 2.8 to 55.5 deg C yielding a Grashof number (based on inner-cylinder diameter) range from 290 to 2.7 × 10 6 . Correlation equations are given to facilitate data presentation and to allow estimation of the inception of this oscillatory flow and its subsequent amplitude, period, and wave length.