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"ABSTRAKThe water-wave interaction with submerged breakwaters is examined to determine the reflection and transmission coefficients. Three types of breakwaters are considered, namely, a submerged breakwater extending from the sea bed until below the waterline, a breakwater extending from above the seawater to some distance below, and a breakwater extending all the way from the seabed with slit at some distance from the bed. In all three cases the breakwaters are assumed to be rigid, thin, and impermeable, and subjected to linear monochromatic waves, and the fluid motion is idealized as linearized, two-dimensional potential flow. A computationally efficient method - an eigenfunction technique with a mixed boundary condition - is used to determine the velocity potential anywhere in the region of flow. The least-square method has been utilized in the solution for the mixed boundary condition. The accuracy of the solution is demonstrated by comparing the numerical values for the transmission coefficient with those obtained from experiments or other analytical solutions but with water depth restrictions. Numerical results in terms of both reflection and transmission coefficients are presented for each case."

"This book comprises selected proceedings of the Fourth International Conference in Ocean Engineering (ICOE2018), focusing on emerging opportunities and challenges in the field of ocean engineering and offshore structures. It includes state-of-the-art content from leading international experts, making it a valuable resource for researchers and practicing engineers alike."

"Metode numerik permodelan aliran air permukaan saat ini berkembang ke arah metode particle-based sebagai alternatif dari metode grid-based. Tujuan dari penelitian ini adalah untuk menguji kemampuan metode Smoothed Particles Hydrodynamics dalam menyimulasi fenomena aliran 3 dimensi pada penyempitan pipa vertikal. Pengujian dilakukan dengan membuat dan meninjau hasil permodelan berdasarkan Hukum Kekekalan Massa dan Energi. Variabel tinjauan hasil simulasi berupa; kecepatan, massa jenis, dan tekanan. Skenario simulasi divariasikan berdasarkan jumlah partikel dan nilai rest density.Hasil simulasi permodelan secara umum menunjukkan peningkatan nilai kecepatan dan penurunan nilai tekanan pada penyempitan pipa, sehingga prinsip Hukum Kekekalan Energi telah terpenuhi meski dalam beberapa skenario nilai tekanannya menurun pada beberapa segmen penyempitan. Selisih nilai massa jenis partikel terhadap massa jenis air masih berfluktuasi dengan persentase antara 0.04% hingga 100%, walau nilai rest density telah divariasikan, sehingga Hukum Kekekalan Massa baru terpenuhi sebagian. Dengan demikian, secara umum hasil penelitian menunjukkan bahwa metode SPH berpotensi mampu untuk menyimulasi fenomena aliran 3 dimensi pada penyempitan pipa vertikal.

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Numerical method of modeling flow of surface water is currently evolving toward particle-based method as an alternative to grid-based method. The purpose of this study is to evaluate the ability of the Smoothed Particles Hydrodynamics method in simulating a 3-dimensional fluid flow through constriction of vertical pipe. Examination of this methods is done by reviewing the results based on the Law of Conservation of Mass and Energy. The scenarios on these simulations are varied by the number of particles and the value of rest density.

The results from these simulations are, generally the value of velocity increase while the value of pressure decrease in the constriction segment, so that the principles of the Law of Conservation of Energy has been fulfilled even though in some scenarios the pressure value declined in some segments of the constriction. The difference percentage between the particle?s density with the rest density value are still fluctuate from 0.04% until 100%, even the value of rest density has been varied, so that the Law of Conservation of Mass is not completely fulfilled. Thus, in general, the results showed that SPH method is able to simulate three-dimensional fluid flow through constriction of vertical pipe."

"This book about the cell-surface interaction, studying cell-surface interactions In vitro : a survey of experimental approaches and techniques, harnessing cell-biomaterial interactions for obsteochondral tissue regeneration, interaction of cells with decellularized biological materials, evaluation of biocompatibility using In vitro methods : interpretation and limitations, artificial scaffolds and mesenchymal stem cells for hard tissues, bioactive glass-based scaffolds for bone tissue engineering, microenvironment design for stem cell fate determination, stem cell differentiation depending on different surfaces, designing the biocompatibility of biohybrids, interaction of cartilage and ceramic matrix, and bioresorption and degradation of biomaterials."

"Kecepatan kapal adalah suatu nilai yang penting guna untuk memenuhi standart kecepatan dinas kapal. Pengoptimalan sistem propulsi kapal adalah faktor yang perlu diperhatikan. Beberapa penelitian untuk meningkatkan sistem propulsi kapal sudah banyak dilakukan, salah satunya adalah wake equalizing ducts dan kort nozzle. Penelitian tersebut bertujuan untuk mengarahkan aliran air lebih banyak dari sisi bawah dan sisi samping lambung kapal menuju ke baling - baling kapal. Cara ini dimaksudkan agar dapat meningkatkan efisiensi baling - baling, yang nantinya akan meningkatkan kecepatan kapal secara langsung. Dengan tujuan yang sama dengan wake equalizing ducts dan kort nozzle, maka water tunnel dirancang dengan rancangan yang lebih sederhana. Water tunnel adalah suatu terowongan air berbentuk kotak lengkung yang terhubung dari bawah lambung kapal ke buritan menuju baling - baling. Water tunnel ini memanfaatkan aliran air bawah lambung kapal untuk mengubah energi mekanik menjadi energi kinetik setelah aliran air masuk ke baling - baling. Cara ini diharapkan dapat mengalirkan air lebih terarah menuju ke baling - baling, sehingga efisiensi baling - baling meningkat, yang dapat terukur langsung melalui kenaikan kecepatan kapal. Penelitian ini dilakukan dengan cara ekperimental dan simulasi untuk mengetahui fenomena yang terjadi akibat penggunaan water tunnel. Cara Eksperimental dilakukan untuk membandingkan kecepatan kapal yang terjadi antara penggunaan water tunnel dan tidak menggunakan water tunnel, dan cara simulai dilakukan guna mengetahui fenomena aliran yang terjadi di dalam water tunnel. Sehingga pada akhir penelitian didapatkan analisa kecepatan yang terjadi akibat penggunaan water tunnel pada kapal pelat datar. Dari hasil uji kecepatan secara eksperimen didapatkan kenaikan 19-32% dengan menggunakan water tunnel pada kapal pelat datar, dan dari hasil simulasi didapatkan kontur kecepatan aliran di dalam water tunnel dengan batasan pengujian yang dihasilkan.

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Ship velocity is the important value to meet the standard of ship velocity service. Optimalization ship propulsion system is a factor that have to consider. Some studies to improving ship propulsion system has been done, one of study is wake equalizing ducts and kort nozzle. In this study aims to direct the flow more water fro the bottom and side of hull towards the propeller. This method is conducted to improve the efficiency propeller, that will increase the velocity of the ship directly. With the same purpose as wake equalizing ducts and kort nozzle, the water tunnel is designed with a simply design. Water tunnel is a duct of water that shaped is curve box and connected from bottom hull ship toward aft propeller. Water tunnel takes the water flow from under the hull to convert mechanical energy to be kinetic energy after the water flow enter propeller. This method is expected to drain the water more directed toward the propeller, so the efficiency would increase, which can be measured directly through the ship velocity increase. The research was done by experimental and simulation to know the phenomenon that occurs due to using water tunnel. Experiment test conducted to compare the velocity ship that happen between unsing water tunnel and not using water tunnel, and with simulation test conducted to know the flow phenomena in water tunnel. So at the end of study was obtained that analisys of the velocity result using water tunnel system on the flat plate ship. Result of the ship velocity test experiment, obtained 19-32% increase by using a water tunnel on a flat plate ship, and from simulation test result obtained the value of contours flow in the water tunnel with boundary of study result."