Turbulent flow visualization in computational and experimental hydraulics

Many practical problems in open channel hydraulics that were traditionally investigated in hydraulic model experiments, are nowadays being solved by using computational fluid dynamics. However, in order to interpret computational results, there is a clear preference among scientists and engineers for visualization in analogy with experimental techniques. One such technique, particle tracing, enables a dynamic (Lagrangian) interpretation of a statically (Eulerian) computed vector field. However, quite often the emphasis in particle tracing is only on the mean flow properties, while effects due to dispersion and mixing are often not accounted for. Hence turbulent flow characteristics have to be incorporated in a visualization system for practical hydraulic engineering problems. The particle tracing technique presented in this case study has been specifically developed to combine both mean and fluctuating velocity vectors, thus simulating stochastic perturbations around mean flow conditions. A number of cases are presented that demonstrate the practical applicability of advanced visualization techniques in realistic engineering studies.