Abstract
Fundamental forms of regression functions are proposed for large bubble lengths, liquid slug lengths, distances between a large bubble and the following large bubble and large bubble period of gas-liquid-solid three-phase slug flow in vertical pipes. They are composed of rations of volumetric flux, viscosity ratio, density ratio, the Froude number, the Reynolds number, and the Weber number. Empirical regression functions were obtained using the experimental data of air-water-aluminum ceramic balls threephase slug flow in the vertical pipes with their diameter 20.9-50.4mm. Diameters of solid particles are 1.14-24.8mm and their densities are 2270-2400kg/m^3. The values of coefficient of determination of their regression functions are larger than 0.9 and the estimated values agree well with the experimental results.