کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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4533861 | 1325227 | 2006 | 16 صفحه PDF | دانلود رایگان |
The physical process of dispersion which can be attributed to turbulence (turbulent diffusion) or shear (shear-augmented diffusion) within the flow field is very important as it ultimately governs the distribution of constituents of interest within the environment. A series of diffusion experiments were conducted in Corpus Christi Bay, TX with the purpose of characterizing turbulent diffusion through dispersion coefficients or turbulent diffusivity, Ki (i=x, y, z) dependent on the degree of randomness or turbulence intensity, I.Measured with a boat-mounted acoustic doppler current profiler (ADCP), the Eulerian velocity time-series of fluid particles in random motion, ui was used in the evaluation of the Eulerian time-scale of turbulence, TE based on the velocity correlation function, RE with TE being related to the Lagrangian time-scale TL through a scaling parameter, β(=TL/TE). Surface currents were obtained with high frequency (HF) Radar equipment deployed over the study area from which the horizontal velocity gradients were determined.Within the spatial scale of the experiment (∼1000 m), the observed low horizontal gradients (∼10−4 s−1) allowed for the generation of velocity time-series from an ADCP mounted on a moving platform. A numerical scheme for evaluating turbulent diffusivity values (Ki=βu′i2¯TE) was developed on the basis of Eulerian current measurements and calibrated through the statistics of an evolving dye patch for the scaling parameter β which in this scheme was found to be in the range 1–3.
Journal: Continental Shelf Research - Volume 26, Issue 20, December 2006, Pages 2629–2644