27 / 94
PHD THESIS
Background
In turbulent free-surface flow, the deformation
of the free-surface leads to entrainment of air
bubbles. To ensure safe operation of hydraulic
structures, and to optimize its performance, the
amount of entrained air and its mixing within the
ow must be accurately predicted.
The hydraulics of aerated flows can greatly
benefit from insights provided by numerical
simulations. An ideal numerical model has to be
fast in the definition of a macroscopic interface
and at the same time be precise enough to
take into account
the formation of
bubbles through the
free surface. Due
its complexity, an
accurate prediction of
the air entrainment
process is an
ambitious goal for
most computational fluids dynamics tools.
Some attempts have been made to capture the
physical behavior of the air entrainment process
into computational fluid dynamicsmodels (CFD).
Nevertheless, more research are needed to get
a reliable solver for the generic air entrainment
phenomena.
Objective
The objective of this study is to investigate
whether a numerical model can reproduce the
air-water interaction in hydraulic structures.
This will be done using the open-source
software, OpenFOAM, which solves the
mass- and momentum equations on a three
dimensional grid. The capacity of the simulation
tool in predicting the air entrainment process
will be investigated, with the aim of improving
the relevant solver.
Department of Civil
and Environmental
Engineering
2016-2020
Numerical Modeling
of Air Entrainment in
Hydraulic Structures
Supervisor
:
Nils Reidar Bøe Olsen
Silje Kreken Almeland
27