Numerical investigation of bubbles in channel flow

Abstract

This master’s thesis aims to study the numerical methods that can simulate the influence of injection of air bubbles under a ship’s hull. The geometry of the hull is simplified to a flat plate and the analysis is only done in two dimensions. An emphasis is given into the prediction of the reduction of the viscous resistance that is observed in experiments. This study is carried out using CFD analysis with the software OpenFOAM. Two frameworks, Eulerian-Eulerian and Eulerian-Lagrangian, that allows the simu-lation of a multiphase flow are set-up and the assumptions behind all the required models are explained. The simulations predicts a gain of eÿciency between 0% and 15% depending on the diameter of the bubbles. Some di˙erences in the results pro-duced by the two di˙erent methods are highlighted and guidance is given on which solver to use for a given case depending on the diameter and the concentration of the bubbles below the plate.