Hasil Pencarian  ::  Simpan CSV :: Kembali

"Lokasi pada pembuluh darah yang memiliki peluang paling besar terjadinya pengendapan plak aterosklerosis adalah zona bifurkasi (percabangan) pada pembuluh darah arteri karotis. Fluida non-Newtonian darah memiliki karakteristik fluida shear-thinning. Simulasi CFD digunakan untuk menganalisis hemodinamik pada aliran pembuluh darah arteri karotis yaitu menggunakan software ANSYS Fluent Student dengan metode finite volume. Geometri percabangan arteri disederhanakan menjadi model benbentuk T-junction dimana merupakan model geometri ideal pembuluh darah dan paling sederhana. Selain itu, fitur alirannya menunjukkan perilaku yang paling umum pada bifurkasi arteri. Digunakan Metode desain eksperimen 2k faktorial untuk menginvestigasi pengaruh ukuran domain aliran masuk dan keluar, dan juga derajat bifurkasi terhadap respons variabel yg berupa nilai kecepatan, Wall Shear Stress (WSS), dan Oscillatory Shear Index (OSI). Hasil dari simulasi ini dapat sangat membantu para ilmuwan medis untuk lebih mudah memprediksi area yang berpotensi untuk membentuk plak aterosklerosis di dalam sistem peredaran darah.

---

The blood vessel that has the greatest chance of atherosclerotic plaque deposition is the bifurcation zone (branching) in the carotid artery. The non-Newtonian fluid of blood has the characteristics of a shear-thinning fluid. CFD simulation was used to analyze hemodynamics in carotid artery flow using the ANSYS Fluent Student software with the finite volume method. The branching geometry of the arteries is simplified into a T-junction model which is the ideal blood vessel geometry model and the simplest to perform simulations. Moreover, its flow features exhibit the most common behavior in arterial bifurcations. The 2k factorial experimental design method was used to investigate the effect of the inflow and outflow domain sizes, as well as the degree of bifurcation on the response variables in the form of velocity values, Wall Shear Stress (WSS), and Oscillatory Shear Index (OSI). The results of this simulation can greatly help medical scientists to more easily predict areas that have the potential to form atherosclerotic plaques in the circulatory system."

"Pipa merupakan sarana transportasi yang tepat untuk mengangkut heavy oil. Fluida non-Newtonian heavy oil memiliki karakteristik fluida shear-thinning. Namun, kendala yang muncul dalam penggunaan pipa sebagai media transportasi heavy oil adalah pressure drop yang tinggi sepanjang pipa. Penyebab dari tingginya pressure drop karena heavy oil memiliki viskositas yang besar sehingga dibutuhkan biaya dan konsumsi energi yang besar juga. Salah satu teknologi yang digunakan di industri migas untuk mengurangi pressure drop tinggi adalah metode core annular flow (CAF). Penelitian ini dilakukan untuk membandingkan penghematan energi aliran laminar pada heavy oil 1 fase dengan metode CAF pada geometri pipa Y-junction. Juga menganalisis hidrodinamika aliran heavy oil 1 fase dalam pipa menggunakan simulasi computational fluid dynamics (CFD) pada ANSYS Fluent Student dengan model viskositas Carreau. Penghematan energi dihitung menggunakan konsumsi energi, power reduction factor, danpressure drop reduction. Penghematan energi tertinggi dan terendah dihasilkan oleh geometri Y50-50 dan Y20-50. Geometri Y50-50 menghasilkan nilai pressure drop reduction hingga 92,91% dengan penghematan energi sebesar 79,30%. Pressure drop tertinggi dihasilkan pada geometri Y50-20 karena mengalami penyempitan pada intersection pipa.

---

A pipeline is an efficient tool for transporting heavy oil. Non-Newtonian heavy oil fluid has the characteristics of a shear-thinning fluid. However, due to its high viscosity, the constraint of using pipelines to transport heavy oil is the high-pressure drop along the pipe. The cause of a high-pressure drop of heavy oil affects the cost and energy consumption. The core annular flow (CAF) method is a technology familiar in the oil and gas industry to reduce pressure drop in pipelines. In this study, energy savings have been served to compare the savings between single-phase oil laminar flow and the CAF method through a Y-junction pipe. Also, to analyze hydrodynamics of heavy oil flow through pipe using computational fluid dynamics (CFD) simulation in ANSYS Fluent Student with Carreau model viscosity. Energy savings are calculated by consumption energy, power reduction factor, and pressure drop reduction. The highest and lowest energy savings are produced by Y50-50 and Y20-50 geometry, respectively. Y50-50 generates pressure drop reduction by 92.91% with energy savings of 79.30%. On the other hand, Y50-20 has the highest pressure drop due to sudden contraction in the intersection of the pipe."

"Green diesel adalah bahan bakar diesel alternatif yang dibuat dari hydrotreating trigliserida yang memiliki alkana rantai lurus C15-C18. Penelitian ini difokuskan pada studi kinetika reaktor trickle-bed untuk memproduksi green diesel melalui reaksi hydrotreating trigliserida, yang diwakili oleh triolein, dengan katalis NiMo/Al2O3. Model yang dibuat adalah model reaktor trickle-bed 2D axisymmetric dengan mempertimbangkan perpindahan massa di fasa gas, cair, dan padatan katalis. Model disimulasikan dengan COMSOL Multiphysics 5.4 dengan menyesuaikan hasil simulasi dengan data eksperimen. Reaktor yang dimodelkan berisi katalis berbentuk bola dengan ukuran 1 mm. Reaktor akan memiliki ukuran diameter 2,01 cm dan panjang 24 cm. Kondisi operasi reaktor akan memiliki suhu umpan 290-330 oC, tekanan 10 dan 15 bar. Nilai faktor pra-eksponensial untuk reaksi hydrotreating trigliserida, reaksi maju isomerisasi C18 (k10), reaksi mundur isomerisasi C18 (k11), reaksi cracking C17 (k12), dan reaksi cracking C18 (k13) berturut-turut adalah 2,9 x 10-37 1/detik, 3,45 x 1028 1/detik, 6,67 x 10-3 1/detik, dan 1,24 x 10-52 1/detik. Energi aktivasi yang didapatkan untuk k10, k11, k12, dan k13 berturut-turut adalah –340,3 kJ/mol, 340,3 kJ/mol, 17,1 kJ/mol, dan –515,3 kJ/mol. Hasil simulasi dan hasil laboratorium mendekati garis linier pada grafik paritas, menunjukkan bahwa hasil simulasi sudah sesuai dengan hasil laboratorium.

---

Green diesel is an alternative diesel fuel made from hydrotreating triglycerides having straight chain alkanes C15-C18. This research is focused on the study of trickle-bed reactor kinetics to produce green diesel by hydrotreating triglycerides, represented by triolein, with NiMo/Al2O3 as catalyst. The model made is a 2D axisymmetric trickle-bed reactor model by considering mass transfer in the gas, liquid, and solid catalyst phases. The model was simulated with COMSOL Multiphysics 5.4 by adjusting the simulation results with experimental data. The modeled reactor contains a spherical catalyst with a size of 1 mm. The reactor will have a diameter of 2.01 cm and a length of 24 cm. The reactor operating conditions will have a feed temperature of 290-330 oC, pressures of 10 and 15 bar. The pre-exponential factor values for triglyceride hydrotreating reaction, forward C18 isomerization reaction (k10), C18 reverse isomerization reaction (k11), C17 cracking reaction (k12), and C18 cracking reaction (k13) were 2.9 x 10-37 1/sec, 3.45 x 1028 1/sec, 6.67 x 10-3 1/sec, and 1.24 x 10-52 1/sec , respectively. The activation energies obtained for k10, k11, k12, and k13 are –340.3 kJ/mol, 340.3 kJ/mol, 17.1 kJ/mol, and –515.3 kJ/mol, respectively. The simulation results and laboratory results are close to the linear line on the parity graph, indicating that the simulation results are in accordance with the laboratory results."

"The effects of the application of a stern hydrofoil on ship resistance were studied numerically using computational fluid dynamics (CFD) and were verified using data from model tests. A 40 m planing-hull Orela crew boat, with target top speed of 28 knots (Froude number, Fr = 0.73), was considered. The stern foil (NACA 64(1)212) was installed with the leading edge positioned precisely below the transom with angle of attack of 2 degrees at elevation 0.853 T below the water surface (where T is the boat’s draft). At relatively low speed (Fr < ~0.45) the application of a stern foil results in an increase in ship resistance (of up to 13.9%), while at relatively high speed (Fr > ~0.55) it results in a decrease in ship resistance (of up to 10.0%). As the Froude number increases, the resistance coefficient (CT) first increases, reaches a maximum value, and then decreases. Its maximum value occurs at Fr ? 0.5, which is consistent with the prediction of a resistance barrier at approximately this Froude number."

"Ship optimization design is critical to the preliminary design of a ship. With the rapid development of computer technology, the simulation-based design (SBD) technique has been introduced into the field of ship design. Typical SBD consists of three parts: geometric reconstruction; CFD numerical simulation; and optimization. In the context of ship design, these are used to alter the shape of the ship, evaluate the objective function and to assess the hull form space respectively. As such, the SBD technique opens up new opportunities and paves the way for a new method for optimal ship design.This book discusses the problem of optimizing ship’s hulls, highlighting the key technologies of ship optimization design and presenting a series of hull-form optimization platforms. It includes several improved approaches and novel ideas with significant potential in this field"

"This book treats Modelling of CFD problems, Numerical tools for PDE, and Scientific Computing and Systems of ODE for Epidemiology, topics that are closely related to the scientific activities and interests of Prof. William Fitzgibbon, Prof. Yuri Kuznetsov, and Prof. O. Pironneau, whose outstanding achievements are recognised in this volume.It contains 20 contributions from leading scientists in applied mathematics dealing with partial differential equations and their applications to engineering, ab-initio chemistry and life sciences. It includes the mathematical and numerical contributions to PDE for applications presented at the ECCOMAS thematic conference "Contributions to PDE for Applications" held at Laboratoire Jacques Louis Lions in Paris, France, August 31- September 1, 2015, and at the Department of Mathematics, University of Houston, Texas, USA, February 26-27, 2016.This event brought together specialists from universities and research institutions who are developing or applying numerical PDE or ODE methods with an emphasis on industrial and societal applications.This volume is of interest to researchers and practitioners as well as advanced students or engineers in applied and computational mathematics. All contributions are written at an advanced scientific level with no effort made by the editors to make this volume self-contained.It is assumed that the reader is a specialist already who knows the basis of this field of research and has the capability of understanding and appreciating the latest developments in this field. "