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).
ملخص البحث بالعربي
عنوان البحث : أجـــــوبة الحافظ محمد البرزالي على سؤالات العز ابن الحاجب في الجرح والتعديل
يهدف البحث : إلى جمع أجوبة الحافظ أبي عبدالله محمد البرزالي في الجرح والتعديل، ودراستها.
يتكون البحث من : مقدمة، وتمهيد، نص السؤالات، وخاتمة، وفهارس.
المقدمة : تسمية الموضوع، وسبب اختياره، وأهميته .
والتميهد : ترجمة مختصرة للحافظ أبي عبدالله البرزالي، والتعريف بأجوبة الحافظ الب
... Show More
Abstract
The relationship between population and development is one of the most interrelated relations in contemporary societies. Therefore it is important focus on the demographic aspects of the population and its integration with developmental aspects, because the population is the makers of development and responsible for its success. The population composition and their qualitative composition are important factors in development. This change in age rate is because of demographic operations which lasted for long time. The change we are talking about is happing currently in Arab cou
... Show More
الجمود المؤسسي واثره في فشل التنمية السياسية : محاولة من اجل بناء مفهوم
وقائع واوراق ندوة (السياسة الخارجية الامريكية في عهد اوباما) التي عقدها فرع الدراسات الدولية في 25 تشرين الثاني 2009
The Negro minority in the United States is associated with social injustice,
political deprivation, and economic oppresion. Its members felt that they are
second-class citizens, and that the acceptance of such status will lead to the
continual oppresion of the Whites upon them. As a result, the educated community
adopted a process to put a framework to their opposition to the former's injustice.
This organised framework is exemplified in the "Niagara Movement," which is
regarded as the first national organisation for Negros. The topic of this study is
chosen due to its historical and political significance.
The study consists of an introduction and five sections. The first section
addresses the preliminaries an
عملية صناعة واتخاذ القرار في السياسة الخارجية للرئيس جورج والكر بوش
شكلت السيطرة العثمانية على العراق حقبة تاريخية مهمة ، حيث وضعت فيها ركائز عدد كبير من الأنظمة الأدارية فغدت الأساس للتنظيمات فيما بعد ومنها الإجراءات الإدارية والقانونية وسبل معالجتها لآزمة الأراضي في بغداد1938-1932.
This study aimed to identify the educational leadership in the light of my theory xy and its relationship to the morale of the managers of the junior high school as the study population consisted of directors of junior high school in the city of Baghdad of six directorates education for the academic year 2013-2014 AD The number of managers (211) as director, and amounted to a sample Search of (150) director and director of the research community overall rate (71%) and represent this community fully representative sample, two tools were used in the study: the first measure of educational leadership in the light of my theory xy and the second tool to gauge morale.
Results concluded that the
... Show Moreمجتمع مدني ام مجتمع اهلي ؟ دراسة لواقع المجتمع المدني في البلدان العربية
تزايد اهتمام الحكومات باختلاف أنظمة الحكم فيها والأفكار السياسية التي تؤمن بها، بالضرائب كأحد أدوات السياسة المالية، تسعى إلى أن تحقق من خلالها أهداف اقتصادية واجتماعية وسياسية فضلا" عن الأهداف المالية، إذ إن السياسة الضريبية تصاغ أهدافها باتساق وانسجام مع أهداف السياسة الاقتصادية بشكل عام، و إنما كانت الضريبة عام، ولما كانت الضريبة على هذا القدر من الأهمية فانه لم يكن مستبعدا" أن تحظى بعناية مشرعي ا
... Show More