A simple predictive tool for analyzing the annular-core flow of two immiscible liquids is presented. The model puts under a common framework all possible flow situations of laminar-laminar, turbulent-turbulent or mixed flow regimes in the two phases involved for wide ranges of viscosity and density ratios. Comparison with available experimental data of pressure drop and in situ hold-up shows a satisfactory agreement. The potential of the core flow configuration for achieving pressure loss reduction and power saving in the transportation of very viscous oils is evaluated, addressing the problem of tube size scale-up.
- annular flow
- core flow