The finite element method is used to predict numerically steady
state, two-dimensional laminar and turbulent thermal buoyant and convective
recirculating flows. The governing equations are solved by
the finite element method using Galerkin Weighting functions, with
velocity, pressure, and temperature as dependent variables.
Turbulent separating, recirculating flow in the complex geometry
of a room with variable inlets, outlets and convective chimney ducts
is investigated. The room is ventilated/air-conditioned utilising
the solar energy via a flat plate collector and solar absorption airconditioning
system. For this purpose the Navier-Stokes, continuity
and general energy equations are solved in a coupled form and in an
uncoupled form and solutions are compared amongst themselves and with
the experimental results of hot wire anemometers and thermocouples.
The parts where turbulent flows occurred especially in the convective
duct and the room, the flows are analysed using the Prandtl-
Kolmöjorov model to depict the effective viscosity. The analogy between
thermal and momentum diffusivity via Prandtl number is used to depict
the turbulent conductivity from the turbulent viscosity. The length
scale of turbulence is specified as an algebraic function of position
from empirical data and experience of other researchers .
energy is expressed as a function of velocity at the nodes together
with the turbulence intensity which varies from ~5% - ~20%. This
turbulence model is used to predict the flow including its recirculations
in the solar ventilated/air-conditioned room, and the fully turbulent convective channel. The analysis includes temperature
and heat transfer predictions in this complex geometry of combined
free and forced convection, together with buoyancy effects and
turbulent transport and recirculations.
Results obtained are compared with the experimental data which
showed very good agreement.
A Doctoral Thesis. Submitted in partial fulfillment of the requirements for the award of Doctor of Philosophy of Loughborough University.