مهندسی مکانیک مدرس

مهندسی مکانیک مدرس

مدلسازی جابجایی ترکیبی با استفاده از مشخصه های چند بعدی

نویسندگان
1 عضو هیأت علمی و مدیر گروه تبدیل انرژی
2 استاد دانشگاه تبریز/دانشکده مکانیک
3 عضو هیات علمی دانشگاه شهید بهشتی
چکیده
در این مقاله یک روش جدید بر مبنای روش مشخصه‌های چند بعدی برای حل معادلات ناویر- استوکس و انرژی در جریان‌های تراکم‌ناپذیر پایا ارائه شده است. روش‌های قبلی بر پایه مشخصه‌ها در جریان‌های تراکم‌ناپذیر، فرض یک‌بعدی بودن موضعی جریان را به کار برده‌اند و در مراجع به خطای ناشی از این ساده‌سازی اشاره شده است. در تحقیق حاضر، از روش مشخصه‌های چند بعدی مصنوعی برای یافتن مسیر انتشار اطلاعات استفاده شده است. معادلات سازگاری و متغیرهای ریمن تعمیم یافته برای معادلات ناویر‌- ‌استوکس و انرژی استخراج شده و از این معادلات برای یافتن شار جابجایی در مرز سلول‌ها استفاده شده است. برای آزمون دقت و سرعت طرح ارائه شده، جریان سیال تراکم‌ناپذیر پایا در داخل حفره مربعی و جریان اطراف استوانه دایره‌ای همراه با انتقال گرما برای دامنه وسیعی از اعداد رینولدز و گراشهف حل شده است. همچنین جهت مقایسه، روش مشخصه‌ها به همراه میانگین‌گیری برای معادله انرژی مورد ارزیابی قرار گرفته است. نتایج بدست آمده بیانگر همگرایی سریعتر روش جدید نسبت به روش مشخصه‌های معمولی و میانگین‌گیری می‌باشد. در اعداد ریچاردسون بالا، روش میانگین‌گیری همگرا نمی‌شود ولی روش ارائه شده در این مقاله، دارای سرعت همگرایی بالایی می‌باشد.
کلیدواژه‌ها

موضوعات


عنوان مقاله English

Multidimensional Characteristic Modeling of Combined Convection Flows

نویسندگان English

Alireza Rostamzadeh khosroshahi 1
seied esmaeel razavi 2
Seyed mehdi Mirsajedi 3
1 Member of academic staff and head of energy conversion group/ Islamic azad university of tabriz
2 School of Mechanical Engineering, University of Tabriz, Tabriz, Iran.
3 Aerospace Engineering Department, Faculty of New Technologies & Engineering, Shahid Beheshti University, Tehran, Iran.
چکیده English

Present study proposes a new multidimensional artificially characteristic-based (MACB) scheme for simulation of combined convection flows. Multidimensional characteristic structure for energy propagation in incompressible flow is derived for the first time. Four pseudo-waves are selected and equations are discretized along them to observe the physical behavior of domain. Viscous fluxes are computed by variables derivatives at the cell interfaces and for time discretization, a 4th-order Runge-Kutta method was used. According to the new scheme, two-dimensional flow with heat transfer in a square cavity and forced convection around a circular cylinder are solved for a wide range of Reynolds and Grashof numbers. Also, for comparison purposes, the CB scheme with averaging for energy equation is used. It was found that MACB has remarkable faster convergence in comparison with CB scheme and averaging methods. Also, by using MACB scheme, maximum permissible CFL number can be increased 80 percent in comparison to CB scheme. At higher Richardson numbers, the conventional flux averaging was failed to converge properly while MACB scheme presents the most rapid convergence. The computed results of MACB scheme are in good agreement with the benchmark solutions.

کلیدواژه‌ها English

Multidimensional characteristic
Artificial compressibility
Navier-Stokes equations
Combined Convection
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