The research focuses on the development of mathematical models for
describing transient
flows within and between connected
fluid-filled
vessels. The
fluid mechanics of connected vessels is of broad interest
and numerous examples may be found in industry, the built environment and the laboratory. This work focuses primarily on the interaction between three connecting vessels and considers two main areas of
application: (i) the so-called `double-tank' method, as used by experimental
fluid dynamicists to stratify environments, and (ii) the passive
transient ventilation of multi-storey buildings.
An analytical description of the double-tank method, a classic example of liquid exchanges under controlled (constant)
flow rates between
horizontally connected vessels, was developed. Subsequently, a new
technique was proposed, modelled and tested which enabled a broader
range of density stratifications to be set up and without the use of
pumps. This technique enabled liquids to drain freely under gravity
from one vessel to another - the rates of liquid transfer no longer constant but functions of the instantaneous liquid depths.
Modelling the fluid mechanics of multi-storey building ventilation added
additional tiers of complexity as air and heat exchanged between rooms
drive turbulent mixing and there is complex feedback between the individual rooms. Three vessels were again considered, two storeys connected to a common atrium, and the development of the buoyancy-
driven
flow following the activation of heat sources was investigated.
A description of the transient response of the ventilation in an atrium
building leading to a steady state, as typically achieved during the
course of a day, was developed. Wind pressure variations and solar
heat gains in the atrium were also incorporated. The effect of atria geometry on the ventilation of adjoining rooms was established and
shown to be analogous to either an `assisting' or an `opposing' wind.
When `opposing', the ventilation
flow rate reduced. For a strongly `opposing' atrium, a reversal in the direction of
flow through the storey
occurred, revealing the possibility of multiple
flow regimes during the
transients - the dynamics of which were explored. Finally, the building
ventilation model was generalised to n storeys (n > 2) connecting to
a common atrium. Controversially, the implications of the predictions
indicate that current atrium designs do not guarantee enhanced
flow
as is generally accepted.