Journal of Engineering Research 2022-03-23T10:38:15+00:00 رئيس هيئة التحرير Open Journal Systems <div id="content"> <div class="content_section"> <p>The Journal of Engineering Research is a peer-reviewed scientific journal issued by the Faculty of Engineering, University of Tripoli - Libya. This journal aims to spread innovative knowledge in the field of engineering sciences and technology. It is an open access online journal that is issued twice a year. A special issue of the journal can be issued if the editorial board deems a need for that. All published research papers are subject to the principles of scientific evaluation in the field of publication and documentation.</p> <p>The journal's activity began with the end of the eighties of the last century, where the first issue was published in March 1989, the second issue was in December 1991, the third issue was in March 1992, and the fourth issue was issued in June 1995. After that, the journal stopped being issued.</p> <p>The journal has been re-issued continuously since 2006, with two issues per year (March and September), where it issued thirty-one issues until the end of March 2021 on the internet.</p> <p>The editorial board seeks to develop it, expand its reach and provide an opportunity for those interested to view it, as all its issues have been uploaded to the journals website on the internet.</p> </div> <div class="content_section"> <h2>The journal vision</h2> <p>Achieving primacy and excellence in the field of publishing scientific engineering research in both Arabic and English, and regional and global spread in the field of scientific publishing.</p> </div> <div class="content_section"> <h2>The journal message</h2> <p>Contribute to the production of knowledge that serves society, and support creativity in the field of engineering sciences by publishing innovative and refereed scientific research.</p> </div> <div class="content_section"> <h2>The journal objectives</h2> <ul> <li>Publishing solid and distinguished scientific research in the field of engineering sciences, which contributes to the progress and development of society.</li> <li>That the journal be the first choice for publishing engineering research, and that it be among the prestigious scientific journals, highly rated in the field of engineering sciences.</li> </ul> </div> </div> <div id="sidebar"> </div> MODELING OF AIDING MIXED CONVECTION IN PARTIALLY HEATED VERTICAL CHANNLES 2022-03-23T10:38:15+00:00 Musa M. Radwan Akram Alhrari <p dir="rtl" align="right">الملخص</p> <p>&nbsp;</p> <p dir="rtl" align="justify"><br>تم في هذه الورقة دراسة الحمل الحراري المختلط للانسياب الرقائقي في قناة رأسية مسخنة جزئياً بتطبيق فيض حراري منتظم محيطياً على الجزء الأسفل من القناة&nbsp;<img src="" width="61" height="13">&nbsp;وعزل الجزء المتبقي من القناة&nbsp;<img src="" width="58" height="13">&nbsp; &nbsp;وذلك باستخدام طريقة (Finite-control volume method) &nbsp;لاستنباط توزيع درجات الحرارة والسرعات للمائع المتدفق انسيابياً عند مقاطع مختلفة من محور القناة متضمناً الجزء المعزول حرارياً. وكذلك شكل خطوط التدفق الانسيابية (streamlines ) عند قيم مختلفة لـGrashof number . تم حل معادلات الاستمرارية (continuity) وقوة الدفع (momentum) والطاقة آنيا باستخدام الطريقة العددية المشار إليها حيث تم دراسة تأثير طول الجزء المسخن على نمط التدفق وأداء نقل الحرارة &nbsp;عند قيمة ثابتة لـ Grashof number وقد أخذ في الاعتبار تأثير الانتشار المحوري (axial diffusion) في معادلات الزخم والطاقة وتم إعطاء اهتمام خاص إلى النسبة Gr/Re2 وتأثيرها على المجالين الهيدروديناميكي والحراري خصوصا في منطقة مدخل القناة عند قيم مختلفة لـGrashof number &nbsp;وقيمة محددة لعدد رينولد Re = 500,&nbsp;<img src="" width="84" height="18">&nbsp;. حيث يحدث انعكاس التدفق بالقرب من المحور في حالة التدفق المتصاعد الساخن. في هذه الورقة تم تعيين وعرض خطوط الانسياب في القناة والانسياب الايزوتيرمي (isotherms) &nbsp;وكذلك حساب توزيع درجات الحرارة&nbsp; والسرعة وعدد نسلت (Nusselt ) الموضعي ومعامل الاحتكاك .<br><br></p> <p>&nbsp;</p> <p dir="ltr" align="left">ABSTRACT</p> <p>&nbsp;</p> <p dir="ltr" align="justify"><br>In this paper laminar mixed convection in partially heated vertical channel was investigated numerically. The temperature profiles at various axial locations, axial velocity profile in the heated part of the channel and streamlines for aiding buoyancy flow are presented. The case of aiding mixed convection is considered, with the lower part of the channel is subjected to uniform heat flux. Conservation equations of continuity, momentum and energy were solved simultaneously using Finite volume method. The effect of the length of the heated section on the flow pattern and heat transfer performance is investigated for given Grashof numbers. The influence of axial diffusion and it's relevant to flow reversal at the entrance region of the channel was taken into account in the momentum and energy equations and particular attention is given to the ratio<img src="" width="51" height="14"><br>The effect of aiding bouncy forces on the hydrodynamic and thermal fields was examined for air with Re = 500,&nbsp;<img src="" width="86" height="15">. Reversal Flow was observed near the axis for aiding buoyancy flow. Streamlines in the channel, isotherms, temperature distribution, and velocity profiles, local Nusselt number and friction factor were presented. The numerical results presented revealed some interesting features which may be summarized as: (i) the effects of the heated part of the channel on the hydrodynamic and thermal fields are demonstrated for│Gr │≥ 105 for aiding flow. (ii) Nusselt number approaches the asymptotic value at the vicinity of the channel wall for Gr ≤ 105. For Gr ≥ 106 the Boussinesq approximation over predicts the overall heat transfer rate. (iii) For Gr up to 4x105 The Boussinesq approximation still predicts reasonably the heat transfer rate. In general, the heated section modifies the flow field and hence the wall convective heat transfer.</p> 2022-03-23T00:00:00+00:00 Copyright (c) 2022