A numerical study of the two-dimensional steady free convection flow in an inclined annulus between two concentric square cavities filled with a porous medium is presented in this paper for the case when the side outer walls are kept with differentially heated temperature while the horizontal outer walls and the inner walls are insulated. The heated wall is assumed to have spatial sinusoidal temperature variation about a constant mean value. The Darcy model is used and the fluid is assumed to be a standard Boussinesq fluid. For the Cartesian coordinate system, the governing equations which were used in stream function form are discretized by using the finite difference method with successive under – relaxation method (SUR) and are solved by Gauss-Siedel iterative method. The upwind scheme was used for the transport terms in the energy conservation equation. The results are presented to demonstrate the streamlines, the isotherms, and the Nusselt number depending on the Rayleigh number ranging from (Ra =10 to 1000), dimension ratio from (Dr = 0.15 to 0.45), and the inclination angle from (= 0o to 45o). Also the effects of the amplitude (=0 to 1) and the wave number (f =0 to 5) of the heated side wall temperature variation on the free convection are investigated. The results show the effect of previous parameters (Ra, Dr,, , and f) on the flow fields and temperature profiles. It also show that the average Nusselt number is a strong function of the Rayleigh number, inclination angle, dimension ratio, and temperature variation. The peak value of the average Nusselt number based on the hot wall temperature is observed to occur at dimension ratio of (0.15), inclination angle of (40.1°), amplitude and wave number (1 & 0.75) for Rayleigh number of (1000).
شهد العصر الذهبي للإسلام تحول أساسي في مجال الزراعة عرف باسم "الثورة الزراعية الإسلامية" أو" الثورة الخضراء" أو "الثورة الزراعية العربية" ، وقد أتاح الوضع الاقتصادي العالمي الذي أسسه التجار المسلمون في جميع أنحاء العالم القديم ، نشر العديد من النباتات والتقنيات الزراعية بين أجزاء مختلفة من العالم ا
... Show MoreThis Study is concerned with The Fast communications in the wars of arab moslims until the middle of fourth century . it pointed to many communications for that , Like using the fast horses , and carrier pigeon , Almanader (Almanawin) wich used to tell for long distances , and drums , trumpets…
The research(the internal and external factors affecting the political system in
PAKISTAN) involves a series of effects interact both internally and external to affect the
stsbility of the political system.
Intrernally there are a lot of powers affecting the political map of PAKISTAN such as
military institution, political parties, judgement, religious schools……etc.of internal
factors, which represent one of the most important pressure points on the system.
Externally one of the most important external factors which affect internal stability is
Pakistani allision to USA in antiterrorism war. The Pakistani military institution was
involved in the war against Pakistani tribes leading to unstable security in Paki
اهتم في الربع الأول بالمفاهيم النظرية للمناهج التي تقع في النقاط الخمس ، النقطة الأولى تتعلق بمفهوم الخطاب والخطاب المادي ، وقلنا أن الرسالة كانت مبنية على الجسد من البداية ، حتى قبل ذلك هناك ستكون فلسفة أو معرفة المنظمة. أما النقطة الثانية فتتعلق بالمفهوم الفينومينولوجي للخطاب ، ونحن في هذه المرحلة أهم الركائز التي قام عليها (إدموند هوسرل) في بناء مفهوم وصفي ضعيف. في النقطة الثالثة نكشف عن الظواهر المتعلقة ب
... Show Moreيعد تحليل السلاسل الزمنية من المواضـيع الهامة في تفسير الظـواهر التي تحدث خلال فترة زمنية معينة. ان الهدف من هذا لتحليل هو الحصـول على وصف وبنـاء أنموذج مناسب من اجل اعطاء صورة مستقبلية واضحة للسلاسل الزمنية المدروسة وان السلاسل الزمنية اهم الادوات المستخدمة في بناء وتقدير والتنبؤ بالظواهر المختلفة وان الاستدامة المالية هي الحالة التي تكون فيها الدولة قادرة على الوفاء بالتزاماتها الحالية والمستقبلية من غي
... Show Moreواقع الدراسات الاورومتوستطية في الجامعات العراقية "دراسة حالة كلية العلوم السياسية - جامعة بغداد"
In the subject area (participation and tandem), the study showed the views of Mr. Sadr in this field when researching first: the issue of the necessity of these two phenomena in the language that some imams of the language and principles called for to discuss and respond to, and
Use the accounting system of responsibility in assessing the performance of the company profit centers of the leather industry Given the importance of the profit centers of the General Company for Leather Industries, where a circle of activity that is accountable responsible for them (the director) about what is happening with costs and achieve revenues other words, the profit center is the beginning of an independent company with revenues and costs contribute to achieving the objectives of the company as a whole, which is to achieve profits, which means the comprehensive work of the centers of the need to evaluate its performance permanent depending on the conversion rates of the Interior. It was relied on the company's production
... Show More