Scale resolving simulation of dispersed bubbly flows - 14155

This work reports the development and application of a new approach to simulate dispersed bubbly flows whose size is larger than the grid size where Lagrangian Particle Tracking (LPT) methods cannot be applied, and yet too small for an accurate Interface Tracking (IT) method. The new approach inherits features of IT and LPT, and is two-way coupling. Governing equations for the continuous phase are solved on Eulerian (static) grid. Bubbles are assumed to have spherical shape, and surface of each bubble is described by the color function on the static grid. Instead of solving advection equation for the color function as one does in IT, the color function is advected in Lagrangian fashion by the velocity calculated from the forces acting on the bubble in the similar way as in LPT. A new method to calculate the undisturbed liquid velocity required to model the forces is proposed in this paper. The two-way coupling (i.e. bubbles induce liquid motion) is accomplished by adding a body force inside each bubble to model the filtered scales due to the usage of coarse resolution per bubble. The method is validated against terminal rise velocity of air bubble rising in stagnant water and its lateral motion in linear shear flows. (authors)