کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
655284 1457638 2013 12 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Numerical analysis and modeling of plume meandering in passive scalar dispersion downstream of a wall-mounted cube
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی جریان سیال و فرایندهای انتقال
پیش نمایش صفحه اول مقاله
Numerical analysis and modeling of plume meandering in passive scalar dispersion downstream of a wall-mounted cube
چکیده انگلیسی
A DNS database is employed to examine the onset of plume meandering downstream of a wall-mounted cube and to address the impact of large-scale unsteadiness in modeling dispersion using the RANS equations. The cube is immersed in a uniform stream where the thin boundary-layer developing over the flat plate is responsible for the onset of vortex-shedding in the wake of the bluff-body. Spectra of velocity and concentration fluctuations exhibit a prominent peak in the energy content at the same frequency, showing that the plume meandering is established by the action of the vortex-shedding. The vortex-shedding and plume meandering display a low-frequency modulation where coherent fluctuations are suppressed at times with a quasi-regular period. The onset of the low-frequency modulation is indicated by a secondary peak in the energy spectrum and confirmed by the autocorrelation of velocity and scalar fluctuations. Unsteady RANS simulations performed with the v2 − f model are able to detect the onset of the plume meandering and show remarkable improvement of the predicted decay rate and rate of spread of the scalar plume when compared to steady RANS solutions. By computing explicitly the periodic component of velocity and scalar fluctuations, the unsteady v2 − f model is able to provide a representation of scalar flux components consistent with DNS statistics, where the counter-gradient transport mechanism that takes place in the streamwise component is also captured by URANS results. Nonetheless, the agreement with DNS statistics for the mean concentration and the plume width is limited by the onset of the low-frequency modulation in the vortex-shedding and plume meandering, giving a challenging modeling issue in the simulation of dispersion using the RANS equations.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: International Journal of Heat and Fluid Flow - Volume 43, October 2013, Pages 137-148
نویسندگان
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