Flow Processes

Abstract

This topic has its origins in the historical studies of hydraulics. It has since been widened to include studies on boundary layers, compressible flow, rarefied gases, plasmas and non-Newtonian flow. In all cases, simplifying assumptions are made to enable mathematical modelling to be achieved, though the resulting equations are sometimes rather intractable. The theoretical modelling was firstly in the form of inviscid flow theory, which was fruitful in solving flow fields at some distance from the solid boundaries. To this was added at a later date, Prandtl’s boundary layer theory, thus bridging the gap between the distant flow field and the solid boundary. Theoretical, semi-theoretical and empirical treatments using dimensionless groups, model testing and computational methods has enabled satisfactory solutions to be found for many important cases. Expert opinion still plays a key role in evaluating results, because in real applications there are usually qualitative and some quantitative factors that are unmodelled.