بررسی تأثیر تشک جلبکی بر الگوی رسوب در جریانهای تکسویه و موج دار

نوع مقاله : مقاله پژوهشی

نویسندگان

1 هیئت علمی دانشگاه ارومیه

2 هیئت علمی دانشگاه پادوا ایتالیا

چکیده

در این تحقیق تاثیر تشک های جلبکی بر الگوی رسوب به صورت آزمایشگاهی مورد مطالعه قرار گرفت. بدین منظور آزمایش هایی در یک فلوم بزرگ برای حالت های مختلف جریان تکسویه و جریان موجدار در شرایط بستر ماسه ای و بستر جلبکی انجام شد. به منظور جداسازی سرعت های موج از تلاطم، از روش چگالی طیف انرژی استفاده شد. نتایج نشان داد که می توان با استفاده از روش چگالی طیف انرژی (PSD)، سرعت چرخشی ناشی از موج را از داده های تلاطم جدا نمود. نتایج الگوی رسوب حاکی از آن است که تغییرات تراز بستر در حالت بستر ماسه ای شدیدتر از بستر جلبکی می باشد. بطوریکه دامنه تغییرات آن در حالت بستر ماسه ای بویژه در جریان موجدار تقریبا 3 برابر حالت پوشش دار می باشد. علاوه بر آن، با افزایش دبی جریان، متوسط تعداد تاج شکنج در هر متر طولی کاهش و طول موج نسبی شکنج افزایش یافت. همچنین نتایج این تحقیق نشان داد که بار بستر با وجود جلبک ها در شرایط جریان تکسویه و جریان موجدار به ترتیب حدود 80 درصد و 15 درصد کاهش می‌یابد.

کلیدواژه‌ها


عنوان مقاله [English]

Investigation of the impact of macroalgal mats on sediments pattern in unidirectional and wave-induced flows

نویسندگان [English]

  • Mohammad Hemmati 1
  • Hojjat Ahmadi 1
  • Stefano Lanzoni 2
  • Vahid Rezaverdinejad 1
چکیده [English]

The impact of macroalgal mats on sedimentation pattern was experimentally.  Studied To achieve this object, a series of experiments were conducted in a large flume for different flow conditions and bed covers. The Power Spectral Density (PSD) method was employed to separate wave-induced velocities from turbulence. The results showed that the separation of wave-induced orbital velocity from turbulence is possible through the Power Spectral Density (PSD) method. The sedimentation results revealed that the bed level variations in bare bed were severer than in an algal bed, so that, the range of variations in bare bed was three times that of algal bed, especially in wavy flow conditions. In addition, the average number of ripple crests per meter decreased and the relative ripple wave length increased with an increase in flow discharge. Also the bedload quantity in the presence of algae decreased by 80% in unidirectional flow (current) while by 15% in wave-induced flow (a combination of wave and current) conditions.  

کلیدواژه‌ها [English]

  • Macroalgal mat
  • sediment pattern
  • wave-induced flow
  • unidirectional flow
  • PSD method
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