کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
7051699 1457380 2018 22 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Characteristics of the wall shear stress in pulsating wall-bounded turbulent flows
ترجمه فارسی عنوان
خصوصیات تنش برشی دیواره در جریان های آشفته محدود ناشی از دیوار
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی جریان سیال و فرایندهای انتقال
چکیده انگلیسی
A pulsating turbulent pipe flow has been investigated experimentally using hot-film anemometry and particle image velocimetry. Particularly, a 'paradoxical phenomenon' that is known to occur for a range of forcing frequencies and time-averaged Reynolds numbers has been investigated in detail. The paradoxical phenomenon is that the oscillating component of the wall shear stress exhibits a smaller amplitude in a turbulent flow compared to in a laminar flow exposed to the same oscillation in the pressure gradient. In here, the phenomenon is explained by splitting the response of the wall shear stress into one contribution resulting from the imposed pressure gradient τ∼p, and a second contribution resulting from the oscillating Reynolds shear stress, τ∼t. At the conditions of maximum reduction of the wall shear stress amplitude, τ∼p and τ∼t are nearly 136° out of phase. The contributions are thus interfering destructively, this being the ultimate reason for the reduced amplitude. It is also shown that the level of reduction is dependent on the imposed forcing amplitude, this in turn residing from a dependence of the time-development of the oscillating Reynolds shear stress on the forcing amplitude.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Experimental Thermal and Fluid Science - Volume 96, September 2018, Pages 257-265
نویسندگان
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