Calculation of streaklines for time periodic flows

The calculation of streaklines for complex time-dependent flows is confronted with severe difficulties due to the huge data sets involved. In the present work we propose a storage reduction method for time-periodic flows. The method is based on the observation that many time-periodic flows can be accurately approximated using a small number of Fourier terms. By storing only the significant harmonics of the Fourier decomposition, the storage (disk space and core memory) required for calculating streaklines can be reduced by one order of magnitude or more. The reduced storage permits the calculation of the streaklines after completing the solution of the equations, rather than calculating a set of predefined streaklines simultaneously with the solution of the flow. This significantly enhances the capability of studying interactively complex flowfields. Test cases confirm the assumption that a small number of Fourier terms is adequate for calculating accurately the streaklines of complex flows.