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Numerical Investigation of Unsteady Mixed Convection Heat Transfer In ventilated enclosure With Different Aspect Ratio
دراسة عددية لانتقال الحراة بالحمل المختلط غير المستقر داخل حيز مهوى لقيم مختلفة من نسبة ارتفاع الحيز الى طوله

Authors: Amir S. Dawood1 د. أمير سلطان داؤد --- Ali A. Mohammed علي عزام محمد
Journal: AL Rafdain Engineering Journal مجلة هندسة الرافدين ISSN: 18130526 Year: 2015 Volume: 23 Issue: 4 Pages: 143-156
Publisher: Mosul University جامعة الموصل

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Abstract

Unsteady mixed convection heat transfer of a laminar fluid flow in ventilated enclosure was studied numerically. Thebottom horizontalsurface was considered isothermal, whereas the other walls were considered adiabatic. The fluid enters into enclosure through a hole located at the bottom of the left vertical wall and exits from the top of the opposite wall. The mathematical model is governed by two dimensional conservations of mass, momentum and energy equations. The numerical simulations of the fluid flow and heat transfer were investigated with a range of Reynolds number (50-500) and Richardson number (0-10), with Prandtl number fixed at 0.71. The effect of the aspect ratio on the fluid flow and heat transfer characteristics in the enclosure was studied in three different values (0.5, 1, 1.5 ). The numerical results showed that the maximum value of the average Nusselt number was achieved at aspect ratio of 0.5. Also, the average Nusselt number increases with the increase of Richardson and Reynolds numbers for whole different cases.

يقدم البحث دراسة عددية لانتقال الحرارة بالحمل المختلط غير المستقر لجريان المائع الطباقي في حيز مهوى. يعتبر الحيز المهوى معزول حراريا عدا السطح السفلي له حيث يعتبر ذو درجة حرارة ثابتة المقدار. يدخل المائع الى الحيز المهوى من المنطقة السفلى للجدار الايسر، في حين يخرج من المنطقة العليا للجدار المقابل. المعادلات الحاكمة التي تُمثّلالانموذج الرياضياتي هي معادلة حفظ الكتلة ومعادلة حفظ الزخم ومعادلة حفظ الطاقة. أُجريت المحاكاة العددية لجريان المائع وانتقال الحرارة لمدى واسع من قيم عدد رينولدز يتراوح بين (500- 50) ومدى من قيم عدد ريشاردسون يتراوح بين (10-0) مع اعتبار قيمة عدد برانتل ثابتة المقدار 0.71. تم دراسة ثلاث قيم مختلفة لتغيير نسبة ارتفاع الحيز الى طوله وهي (0.5 , 1 , 1.5 )، ومدى تأثيرها على خواص الجريان وانتقال الحرارة خلال الحيز المهوى. اوضحت النتائج ان معدل عدد نسلت يبلغالقيمة العظمى له عندما تكون نسبة ارتفاع الحيز الى طوله 0.5. وكذلك اوضحت النتائج ان معدل عدد نسلت يزداد بزيادة كل من عدديرينولدزوريشاردسون ولجميع الحالات المدروسة.


Article
NUMERICAL INVESTIGATION OF MIXED CONVECTION BY NON-CONCENTRIC POSITIONS OF ROTATING CIRCULAR CYLINDER IN SQUARE ENCLOUSRE

Authors: Mushtaq Fasiel --- Duraid F. Maki --- Farooq Hassan Ali
Journal: Al-Qadisiyah Journal for Engineering Sciences مجلة القادسية للعلوم الهندسية ISSN: 19984456 Year: 2018 Volume: 11 Issue: 1 Pages: 55-79
Publisher: Al-Qadisiyah University جامعة القادسية

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Abstract

In this work numerical investigation of mixed convection by non-concentric different positions of rotating circular cylinder in square enclosure is investigated. The assumption of using six rotating cylinders at constant temperature Th and square closed enclosure with temperature Tc for all walls are maintained. Continuity, Momentum and energy governing equations are solved by using finite volume technique using Ansys-Fluent 16 commercial code with two dimension and steady state case. Richardson number (Ri=Gr/Re2) varying over the wide range of 0.1, 1, 10,100, 1000 and ∞. This research investigate the effect of changing the rotating circular cylinder positions along the vertical centerline on the fluid flow and heat transfer inside the enclosure. Six different positions are tested. The phenomenon inside the square enclosure is mathematically analyzed. A streamlines, isothermal patterns, local Nusselt numbers, and average Nusselt numbers are calculated. The analytical results give that, the Richardson numbers is playing the dominant role on temperature distributions and flow patterns inside the enclosure. The average Nusselt number variation demonstrates the best location of rotating cylinder which gives best heat transfer value. The bottom left corner (P4) is the best location for hot rotating cylinders. While the rotating in middle right (P6) is the inferior position


Article
STUDY OF MIXED CONVECTION IN A SQUARE ENCLOSURE WITH A ROTATING CIRCULAR CYLINDER AT DIFFERENT VERTICAL LOCATIONS
دراسة للحمل المختلط داخل حيز مربع بوجود اسطوانة دائرية دوارة في مواقع عمودية مختلفة

Author: Farooq Hassan Ali فاروق حسن علي
Journal: Iraqi journal of mechanical and material engineering المجلة العراقية للهندسة الميكانيكية وهندسة المواد ISSN: 20761819 Year: 2011 Volume: 11 Issue: 2 Pages: 242-261
Publisher: Babylon University جامعة بابل

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Abstract

AbstractMixed convection in a square enclosure with a rotating circular cylinder located at different vertical locations is numerically studied. The horizontal and vertical walls are kept at constant temperature Tc, while the surface of the rotating circular cylinder is maintained at a constant temperature Th. A two dimensional solution for steady laminar mixed convection is obtained by solving governing equations in stream function-vorticity form with finite difference technique for different Richardson number (Ri=Gr/Re2) varying over the range of 0.0 to 10. Depending on the Richardson number the convection phenomena inside the enclosure becomes natural, mixed, and forced convection. For the first time this study goes to investigate the effect of changing the rotating circular cylinder positions along the vertical centerline on the fluid flow and heat transfer inside the enclosure. The phenomena inside the enclosure is analyzed through a streamlines, isothermal patterns and average Nusselt numbers. The results show that the flow field and temperature distribution inside the enclosure are strongly dependent on the Richardson numbers and the position of the rotating circular cylinder, and the enclosure has maximum heat transfer rate when the cylinder near the bottom wall (δ=0.25).

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