DENSITY OSCILLATOR - ANALYSIS OF FLOW DYNAMICS AND STABILITY

Two open containers filled with fluids of different density and connec ted by a vertical capillary tube can approach their thermodynamical eq uilibrium via an oscillatory flow. The temporal evolution of flow velo cities was measured quantitatively. Data on the critical values determ ining the flow reversal are extracted yielding a simple dependence of the critical level of heavy fluid as a function of the density ratio a nd the length of the capillary. A novel theoretical description of the system is presented which is based on a one-fluid model and a steady- state approximation for a two-dimensional flow. Theoretical results ar e in good agreement with the experimental data. [S0031-9007(98)06728-3 ].