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شبیه‌سازی عددی پدیده گذار داخلی با استفاده از مدل اصلاح شده γ-Reθ | ||
| نشریه مهندسی مکانیک امیرکبیر | ||
| مقاله 4، دوره 54، شماره 7، مهر 1401، صفحه 1533-1552 اصل مقاله (3.81 M) | ||
| نوع مقاله: مقاله پژوهشی | ||
| شناسه دیجیتال (DOI): 10.22060/mej.2022.21138.7383 | ||
| نویسندگان | ||
| محمدعلی مدرسی1؛ قاسم حیدری نژاد2؛ رضا مداحیان* 1؛ بهار فیروز آبادی3 | ||
| 1گروه تبدیل انرژی، دانشکده مهندسی مکانیک، دانشگاه تربیت مدرس، تهران، ایران | ||
| 2تربیت مدرس | ||
| 3شریف*مکانیک | ||
| چکیده | ||
| شبیه‌سازی عددی پدیده گذار یکی از چالش‌ها در شبیه‌سازی جریان‌های آشفته در هر دو نوع از جریان‌های داخلی و خارجی است. در مطالعه حاضر، ضرایب مدل گذار چهار معادله‌ای γ-Reθ بر اساس فیزیک گذار در جریان داخلی به نحوی اصلاح می‌شود که طول ورودی در جریان داخلی بدرستی پیش‌بینی شود. برای اعتبارسنجی، جریان داخلی در شش هندسه متفاوت شبیه‌سازی شد تا جامعیت مدل در پیش‌بینی پدیده گذار در فیزیک‌های مختلف مشخص شود. جریان درون مجرای سه بعدی، دو لوله متقارن محوری، یک لوله تنگ شونده-بازشونده، دو صفحه موازی و پله معکوس در محدوده اعداد رینولدز 103×2 تا 105×3 شبیه‌سازی گردید. متغیرهای جریان نظیر سرعت متوسط، ضریب اصطکاک پوسته‌ای، ضریب اصطکاک در ناحیه توسعه یافته و طول بازچسبانی با نتایج تجربی، تئوری و نتایج حاصل از شبیه‌سازی گردابه‌های بزرگ مقایسه شد. با مقایسه نتایج سرعت متوسط با روابط نیمه تجربی و داده‌های تجربی، مشاهده شد که مدل اصلاح شده توانایی تخمین مناسبی از طول ورودی در جریان داخلی را در مقایسه با داده‌های تجربی دارد. علاوه‌براین، مقدار خطا در پیش‌بینی ضریب اصطکاک در ناحیه توسعه یافته و طول بازچسبانی با استفاده از ضرایب اصلاح شده به ترتیب بیش از 7/6 و 26/7درصد در مقایسه با مدل‌های پیشین کاهش یافت. | ||
| کلیدواژه‌ها | ||
| جریان داخلی؛ مدل گذار γ-Reθ؛ متوسط‌گیری رینولدز؛ شبیه‌سازی عددی | ||
| عنوان مقاله [English] | ||
| Numerical Investigation of Internal Flow Transition Using Modified γ-Reθ Model | ||
| نویسندگان [English] | ||
| Mohamad Ali Modaresi1؛ Ghassem Heidarinejad2؛ Reza Maddahian1؛ Bahar Firoozabadi3 | ||
| 1Tarbiat Modares University, Tehran, Iran | ||
| 2Faculty of Mechanical Engineering, Tarbiat Modares University, Tehran, Iran | ||
| 3Sharif University of Technology | ||
| چکیده [English] | ||
| The numerical investigation of Transition is one of the challenging issues in turbulence modeling. In the present study, the coefficients of the γ-Reθ model are modified based on the physics of internal flow transition to capture the entrance length properly. To validate the model, the internal flow is simulated using six test cases. A 3D duct, two smooth axisymmetric pipes, a 3D stenosis pipe, two parallel plates, and the backward-facing step configurations are considered at different Reynolds numbers from 2´103 to 3´105. The flow variables, including the average velocity field, friction factor, fully developed friction factor, and the reattachment length are compared against the experimental, theoretical and large eddy simulation results. By comparing the results of average velocity against the semi-empirical relations and experimental data using new coefficients, it is observed the model can estimate the entrance length in accordance with experiments. The earlier coefficients lead to a reduction of entrance length by increasing the Reynolds number. Furthermore, the error percentages reduce by more than 7.6 and 26.7 percent using new coefficients rather than earlier models for fully developed friction factor and reattachment length, respectively. | ||
| کلیدواژه‌ها [English] | ||
| Internal flow, γ-Reθ transitional model, Reynolds-averaged Navier–Stokes equations, Numerical simulation | ||
| مراجع | ||
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