Dr Robert Barber is a Research Officer at the Computational Science and Engineering Department of Daresbury Laboratory in Warrington, Cheshire. This Laboratory, which is a Centre of Excellence supported by the Research Councils of the UK, is reknown throughout the world.

Robert graduated as a Civil Engineer from Salford University where he also completed a PhD on Computational Fluid Dynamics and the solution of shallow water equations. Upon completion of his PhD, he was appointed as a Lecturer in Hydraulics, also at Salford where he carried out research in Environmental Modelling, estuarial and tidal flow, harbours and reservoirs. From there he moved to his current position at the Daresbury Laboratory. There he carries out research on microfluids, specialising in low Re number fluids.

Robert's lecture was on "Numerical Simulation of Rarefied Gas Flows in Microfluid Devices". These fluids behave differently from other cases for which the standard Navier Stokes equations apply. The gas is rarefied and the most striking effect in this case is the occurrence of slip at the boundaries. The amount of slip at the wall depends on the shear stress and is governed by an equation defined as late as 1961. Experimental results have validated this assumption for microfluid.

The analysis uses a modified Navier Stokes Solver for a range of Re numbers between 1 and 400, with Knudsen numbers ranging from 0 down to 0.1. The results seemed to confirm the new theories developed by Dr Barber.

An interesting application described by the lecturer was of flow past a microsphere in a circular pipe, a configuration that has many uses in practice. This case has also an analytical solution for the drag.

The conclusions of his talk were that scaling down gives rise to numerous challenges. Accurate numerical models are vital in the design and optimisation of microfluid devices. Designing microfluid systems to operate over a wide variety of Knudsen numbers are challenging due to the changing flow regime and assumptions.

The world market for Microsystem Technologies (MST) is growing rapidly. The invention and development of microfluidic products continues to increase and it is expected that the number of products will double in two years' time.

There are numerous applications of them in Medical Systems while their use in Environmental cases will also grow. There is a clear and strong shift from aerospace and other similar applications into the Medical Field.