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Multi-horizontal submerged jets stilling basins have been utilized in large-scale water conservancy and hydropower projects due to its stable flow pattern, high energy dissipation rate and less atomization. This study employs vorticity criterion, Q criterion, λ2 criterion and Ω criterion to investigate the characteristics of vortex formation and turbulent dissipation in multi-horizontal submerged jets stilling basins with various configurations, including crest overflowing orifice alone (COO), combination of crest overflowing orifice and mid-discharge orifice (COO-MO) and mid-discharge orifice alone (MO). The results indicate that the Q criterion and λ2 criterion are effective in identifying vortex structure within multi-horizontal submerged jets stilling basin. Specifically, the stronger intensity of vortex structure and vortex dissipation are mainly distributed in the vicinity of the vertical drop, which gradually weakens for the increasing distance to the vertical drop. Furthermore, the intensity and number of vortexes with COO-MO are the largest. This conclusion can provide guidance for energy dissipation and bottom protection of stilling pool. [ABSTRACT FROM AUTHOR]

The circulating jet tank (CJT) has been an alternative piece of equipment for mixing instead of the bottom-stirring tank, which is widely used in industrial applications. The recurrence plots (RPs) and recurrence quantification analysis (RQA) of pressure fluctuation signals (PFS) in the novel CJT were employed to reflect the chaotic extent of jet mixing. The recurrence rate, determinism and averaged diagonal line length of PFS were evaluated at different Reynolds numbers, radial positions and axial positions. The profiles of recurrence rate, determinism and averaged diagonal line length had similar tendency with the increasing Re, which showed that the determinism of PFS increased and the randomness of the chaotic system became small. With the increase in z/H, the recurrence characteristics of PFS at θm = π/6 gradually increased, which were smaller than that of other θm. The results of this study provide a deep understanding of the hydrodynamics in the CJT, and thus lay a foundation for further design optimization. [ABSTRACT FROM AUTHOR]