A critical comparison of Lagrangian methods for coherent structure detection

摘要: We review and test twelve different approaches to the detection of finite-time coherent material structures in two-dimensional, temporally aperiodic flows. consider both mathematical methods diagnostic scalar fields, comparing their performance on three benchmark examples: quasiperiodically forced Bickley jet, a two-dimensional turbulence simulation, an observational wind velocity field from Jupiter's atmosphere. A close inspection results reveals that various often produce very predictions for structures, once they are evaluated beyond heuristic visual assessment. As we find by passive advection set candidates, false positives negatives can be produced even some mathematically justified due ineffectiveness underlying coherence principles certain flow configurations. summarize inferred strengths weaknesses each method, make general recommendations minimal self-consistency requirements any Lagrangian technique should satisfy.