Bubble and Droplet Dynamics are Studied Numerically Using Partitioned Solvers

Abstract

This article explains how to use partitioned
solvers to simulate bubbles and droplets. A
black box fluid solver is used to model the
flow in the liquid. A structural solver
determines the interface position. To avoid
divergence, implicit coupling it is necessary to
use implicit stepping at a time step's initial
iterations since there is a significant
interaction between the two solvers.
Consequently, a reduced order model of the
fluid solver in a black box is used during the
coupling rounds based on modal analysis.
This model is used to show the production
showing a rising bubble in a stagnant liquid,
an oscillating liquid droplet, and a bubble at
the end of a vertical needle immersed in
quiescent water. Using reduced-order model
of the fluid solver to obtain implicit coupling
between both solvers, the position of the
interface is computed using a structural
solver. The reduced order model is
constructed during the coupling iterations of
a time step using modal analysis as its
foundation. Three axisymmetric problems are
addressed by this model: a water droplet
oscillating in air; an air bubble rising in
stagnant mineral oil; and the development
and separation of an air bubble from a
vertical needle immersed in water that is
quiescent growth and detachment of an air
bubble from a vertical needle, submerged in
quiescent water.