بررسی رژیم‌های مختلف جریان با استفاده از گستره‌ای از مدل‌های گذار در جریان‌های داخلی

نوع مقاله : مقاله پژوهشی

نویسندگان

دانشکده مهندسی مکانیک، دانشگاه تربیت مدرس، تهران، ایران

چکیده

پیش‌بینی رفتار جریان سیال در ناحیه گذار، کلید حل بسیاری از مسائل علمی است. محققین تلاش‌های بسیاری در زمینه ارائه و بهبود مدل‌هایی برای تخمین رفتار جریان سیال در این ناحیه انجام داده‌اند. در این جریان‌ها معادلات حاکم، شامل ناویر-استوکس در کنار مدل‌های انتقال تنش برشی به‌صورت هم‌زمان برای شبیه‌سازی جریان حل می‌شوند. ضرایب بسیاری در معادلات حاکم وجود دارند که شبیه‌سازی جریان سیال را تحت تأثیر قرار می‌دهند. در این پژوهش، مدل گذار انتقال تنش برشی با تغییر دو ضریب در معادلات گذار مورد ارزیابی قرار گرفت و با اعمال ترکیبی از این ضرایب، شبیه‌سازی گذار انجام شد. به منظور ارزیابی دقت ضرایب مدل ارائه شده در شبیه‌سازی، این ضرایب برای شبیه‌سازی سه مسأله جریان داخلی مختلف شامل لوله با سطح داخلی صاف، دو صفحه موازی و یک پله مورد استفاده قرار گرفت. پارامترهای مختلف همچون ضرایب اصطکاک در ناحیه ورودی و توسعه یافته و طول جدایش مورد بررسی قرار گرفتند. یک مقایسه میان نتایج حاصله از ضرایب مدل ارائه شده و داده‌های تحلیلی و تجربی حکایت از دقت خوب این ضرایب در پیش‌بینی جریان سیال دارد. علاوه بر این، در نتایج حاصله از اعمال ضرایب در مدل ارائه شده، طول ورودی جریان در جریان‌های آشفته و گذار به‌خوبی پیش‌بینی شده است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Investigation of Different Internal Flows Using Different Transitional Models

نویسندگان [English]

  • mohammadali modaresi
  • amir yousefi
  • Ghassem Heidarinejad
Department of Mechanical Engineering, Tarbiat Modares University, Tehran, Iran
چکیده [English]

Prediction of flow behavior in the transition region is the key issue in many scientific problems. Many attempts have been made by researchers to propose and modify the models estimating the flow behavior in this region. In these flows, the governing equations, including the continuity, the Navier-Stokes, and the transmittance along with the Shear Stress Transport models are solved simultaneously to predict the flow behavior. There are several coefficients in the governing equations which affect the flow simulation. In this study, the transitional shear stress transport model is modified by altering two coefficients in the intermittency equation. A combination of these coefficients is implemented, and the effects are studied. To assess the accuracy of the proposed coefficients in simulation, they are applied to three individual internal flows, including a smooth axisymmetric pipe, two parallel plates, and a backward-facing step. Different variables such as the friction factor coefficient, fully developed friction factor, and the reattachment length are explored. A comparison between the results and both analytical and experimental data confirms a good accuracy in the predictions. Furthermore, using the presented models the entrance length is well predicted in turbulent and transitional flows.

کلیدواژه‌ها [English]

  • Internal flows
  • Turbulence model
  • Transitional shear stress transport
  • Numerical simulation
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