Condition for non-oscillatory solution for scalar convection-dominated equation

The scalar convection-dominated flows are found in different science and designing applications which incorporates those concerning the computational fluid dynamics problems of mesh structure in the numerical estimations. These flows are thus essential in nature. Despite the fact that these types of flow have been widely discussed among fluid dynamists, the contribution of mesh and flow parameters in predicting spurious-oscillation free solutions remains unclear. In this research, the significance of the connections between the mesh structure and the scalar convectiondominated flow parameters is accentuated. A systematic technique is applied in the setting of the parameters of interest. In particular, we present the a priori formulation of condition to avoid spurious oscillatory solutions, which depends on both Peclet number as well as the number of grid. The condition is useful in a more efficient decision-making in the selection of the computational domain grid, and in eradicating some heuristic parts of the scalar concentration estimate. The results of the test case affirm the consistency of the condition. It is found that, given the right constant value in the amplification factor term within the spatial error growth model, the condition is able to capture the presence of kinks which mark the beginning of the oscillations

Non-oscillatory Spatial Solutions Criterion for Convection-Diffusion Problem

The fact that the convection-diffusion problems are essential in nature is supported by the presence of such problems in vast number of applications in both science as well as engineering. Some of these applications involve the computational domain’s grid structure issues in the numerical experiment of fluid dynamics. The paper highlights the important role of convection-diffusion flow parameters in the construction of the grid structure. We propose the a priori criterion formulation to avoid non-oscillatory solutions which is based on both Peclet and grid  numbers, and serves as a systematic approach in setting grid related parameters of interest. Aiming at a more efficient process in choosing grid structure for computational domain, the criterion functions as a standard which also eliminates heuristic process in the scalar concentration prediction. The test cases’ calculated results verify the consistency of the criterion

Comparative Study of Uniform and Graded Meshes for Solving Convection-Diffusion Equation with Quadratic Source

Due to its fundamental nature, the problems of convection-diffusion are discussed in various aviation, science and engineering applications. Among major applications are in the study of the dynamics of aircraft wake vortex and its interaction with turbulent jet which is a very serious hazard in aviation. Other applications include those in the investigation of intrusive sampling of jet engine exhaust gases, and the effectiveness of hot fluid injection in the removal of ice on aircraft wings. The numerical solutions of convection-diffusion require proper meshing schemes. Among major meshes in computational fluid dynamics are those of uniform, piecewise-uniform, graded, and hybrid over which the solutions of discretized governing equations are found. Bad solutions as spurious fluctuations, over- or under-predictions, and excessive computation time might be the results of unwitting application of the meshes. Accentuating comparative effectiveness of two meshes, namely uniform mesh and graded mesh with mesh expansion factor, this paper takes the solution of a convection-diffusion equation with quadratic source term into account. The problem is solved by assigning several values of mesh expansion factor to graded mesh, while mesh number is kept constant. The factors are calculated based on the generalization of their logarithmically linear relationship with low Peclet numbers derived in previous work. Based on the values of Peclet number, five test cases are considered. Graded mesh is proven relatively more robust, particularly due the solution on the mesh being free from spurious fluctuation. Furthermore, the accuracy level of the solution of up to two order of magnitude higher is obtained. The mesh expansion factor therefore contributes to a stable and highly accurate solution corresponding to all interested Peclet numbers

Formulation of low peclet number based grid expansion factor for the solution of the convection-diffusion equation

Convection-diffusion problems, due to its fundamental nature, are found in various science and engineering applications. In this research, the importance of the relationship between grid structure and flow parameters in such problems is emphasized. In particular, we propose a systematic technique in the selection of the grid expansion factor based on its logarithmic relationship with low Peclet number. Such linear mathematical connection between the two non-dimensional parameters serves as a guideline for more structured decision-making and improves the heuristic process in the determination of the computational domain grid for the numerical solution of convection-diffusion equations especially in the prediction of the concentration of the scalar. Results confirm the effectiveness of the new approach

LAPORAN KASUS : EPILEPSI BANGKITAN UMUM TONIK-KLONIK PADA PASIEN LAKI – LAKI BERUSIA 22 TAHUN

Epilepsi adalah penyakit dengan gejala kompleks dengan beberapa faktor risiko dan dalam banyak kasus memiliki kecenderungan genetik yang kuat, dibandingkan dengan kondisi dengan ekspresi tunggal dan penyebab tunggal. Komorbiditas semakin diakui sebagai penanda etiologi dan prognostik yang penting. Obat anti kejang menekan kejang hingga dua pertiga, jika tidak lebih, dari semua individu tetapi tidak mengubah prognosis jangka panjang. Epilepsi merupakan beban utama dalam hal kualitas hidup, morbiditas, dan risiko kematian dini, terutama pada mereka yang terus mengalami kejang. Operasi epilepsi adalah cara paling efektif untuk mencapai kebebasan kejang jangka panjang, tetapi hanya merupakan pilihan pada beberapa orang dengan epilepsi yang resistan terhadap obat. Dengan pemahaman yang lebih baik tentang epileptogenesis, determinan epigenetik, dan farmakogenomik, muncul harapan untuk perawatan farmakologis dan nonfarmakologis yang lebih baik, memodifikasi penyakit, dan kuratif. Laporan kasus ini membahas epilepsi bangkitan umum tonik-klonik pada pasien laki – laki berusia 22 tahu

Pembentukan nilai-nilai murni masyarakat Semai melalui konsep pandang dunia (world view): Satu analisis awal

Masyarakat Pribumi atau lebih dikenali sebagai orang asli adalah merupakan masyarakat yang mempunyai susur galur hubungan dengan zaman Mesolitik dan Paleolitik. Merekalah yang mempunyai status penduduk terawal dan telah mencorakkan negara kita. Mereka sering dilabel sebagai tidak bertamadun dan kuno serta sering ditindas oleh pihak-pihak tertentu. Tetapi sebenarnya mereka mempunyai tamadun yang tersendiri dan hebat. Juga harus diingat, didalam masyarakat mereka, tidak berlakunya perbuatan jahat dan keji seperti membunuh, merogol, mencuri, sumbang mahram, khianat dan lain-lain lagi sebagaimana yang dilakukan oleh kita, yang kononnya masyarakat bertamadun. Mereka berjaya membina masyarakat yang harmoni dan sejahtera hasil daripada konsep pandang dunia dan pengukuhan sistem kepercayaan terhadap kuasa-kuasa ghaib. Oleh itu tulisan ini akan melihat apakah nilai-nilai murni yang telah dijelmakan melalui pegangan kepada konsep pandang dunia ini serta apakah lebihnya masyarakat peribumi ini berbanding kita