This report consists of an account of work done under IFPRI contract in Cambridge University during the year to November 1984. The principai achievements during that time are:
1. The construction and commissioning of an aerated flow rig.
2: The performance of some preliminary experiments in the rig, whose results are evaluated in this report.
3. The completion of the theoretical work undertaken previously.
Also included is a proposal for the continuation of the work.