PARAMETRIC STUDY OF SINGLE AIR BUBBLE RISING THROUGH DIFFERENT SALINITY WATER COLUMN USING VOLUME OF FLUID (VOF) TECHNIQUE

The rising air bubbles in a liquid due to gravity has been researched for many years and remain a fascinating subject today. The 2-D Volume of Fluid (VOF) method and the CFD technique were employed for simulating. The dynamic meshing technique is applied to simulate the hydrodynamics of rising air bubbles in a liquid water column via the User Defined Function (UDF) code in the C++ environment was developed to evaluate bubble rising through the water column with different salinity. The rising of air bubble through a stagnant water column has been considered, and the influence of column dimension, bubble size, and aspect ratio on the rising velocity and some parameters (Reynolds number, Re, Eotvos number, Eo, Weber number, We, Morton number, Mo, Drag coefficient, CD, Capillary number, Ca, and Flow number, FN are investigated. The obtained results showed that the bubble rising velocity increases with the bubble size. The bubble shapes vary with the diameter due to the effect of varying drag forces.The drag coefficient is reduced from 2.85 to 0.4 as the Reynolds number increases from 20 to 1475.The maximum rising velocity increases by 75% when the Eotvos number increases from 700 to 950, while the Weber number increases by 60% when the bubble size increases from 5 to 7 mm. A good agreement was obtained between the rising velocity predicted in the simulation and that obtained from the literature.