  High-fidelity flow simulations are indispensable when analyzing systems
exhibiting multiphase flow phenomena. The accuracy of multiphase flow
simulations is strongly contingent upon the finest mesh resolution used to
represent the fluid-fluid interfaces. However, the increased resolution comes
at a higher computational cost. In this work, we propose algorithmic advances
that aim to reduce the computational cost without compromising on the physics
by selectively detecting key regions of interest (droplets/filaments) that
require significantly higher resolution. The framework uses an adaptive
octree-based meshing framework that is integrated with PETSc's linear algebra
solvers. We demonstrate scaling of the framework up to 114,688 processes on
TACC's Frontera. Finally, we deploy the framework to simulate one of the most
resolved simulations of primary jet atomization. This simulation -- equivalent
to 35 trillion grid points on a uniform grid -- is 64 times larger than the
current state-of-the-art simulations and provides unprecedented insights into
an important flow physics problem with a diverse array of engineering
applications.
