I would like to thank my supervisor, Clive Greated, for
his suggestions and support.
I would also like to thank Paul Stansell for numerous useful discussions
and for proof reading this thesis; Roger Kingdon for his help and
encouragement;
Alastair Martin for his insight into internal waves and for allowing me
to reproduce some of his results;
and Edinburgh Parallel Computing Centre (EPCC) for allowing
me time on the Connection Machine CM200.
The financial support of SERC is gratefully acknowledged.