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"ABSTRAKThis paper is an attempt at a systematic approach to the flow field analysis in the case of air flowing through a straight channel with a circular bump. The results of the authors own experimental measurements are compared to those obtained by means of both an in house and a commercial CFD code. Apart from the RANS method, which is commonly used in engineering applications, a decision was made to use the URANS and LES methods, which are available both in the in house academic code and in the commercial program. The comparison between the calculation results is performed using what is referred to as the numerical Schlieren image, which for the RANS calculations is compared to the Schlieren image obtained from experimental testing."

"The aim of this paper it to review various scale approaches to the blood flow modelling. Blood motion may be described by three types of mathematical models according to the observed scales or resolutions,namely microscopic,mesoscopic and macroscopic descriptions. The above approaches are discussed together with their advantages and disadvantages. Several results of mesoscopic simulations are presented with particular attention paid to mesoscale semi continuum models suitable for real time blood flow visualisation."

"This textbook provides a step-by-step approach to numerical methods in engineering modelling. The authors provide a consistent treatment of the topic, from the ground up, to reinforce for students that numerical methods are a set of mathematical modelling tools which allow engineers to represent real-world systems and compute features of these systems with a predictable error rate. Each method presented addresses a specific type of problem, namely root-finding, optimization, integral, derivative, initial value problem, or boundary value problem, and each one encompasses a set of algorithms to solve the problem given some information and to a known error bound. The authors demonstrate that after developing a proper model and understanding of the engineering situation they are working on, engineers can break down a model into a set of specific mathematical problems, and then implement the appropriate numerical methods to solve these problems."

"Kebutuhan udara bersih menjadi keharusan di ruang kelas, terlebih di era post-pandemi. Oleh karena itu perlu dilakukan simulasikan laju aliran di kelas yang diberikan air purifier dengan tujuan untuk melihat persebaran dan distribusi dari alir udara di dalam ruang kelas tersebut. Simulasi pada ANSYS CFX 2019 berbasis pada 3D Model yang dibuat bedasarkan pengukuran ruang sebenarnya. Simulasi dilakukan dengan batasan kelas pada variasi flow rate untuk K.101. Hasil yang diukur berupa grafik beserta visual dari kontur dan vektor Age of Air dan Velocity yang didapatkan dari titik koordinat yang tersebar di kelas. Dari grafik ditunjukan bahwa terjadi kecenderungan kenaikan nilai Age of Air seiring dengan berkurangnya nilai flow rate dalam cubic feet per minute di semua titik koordinat. Selain flow rate, ketersediaannya outlet sebagai salah satu tempat keluarnya udara mempengaruhi Age of Air dan Velocity. Pada vektor Velocity, pada bukaan jendela, dan pintu, terdapat pertukaran udara yang ditunjukkan oleh arah udara. Hal ini membuktikan terjadinya sirkulasi dengan disuplainya udara segar ke ruangan. Perbedaan flow rate antara data dengan menggunakan nilai 5 Air Change per Hour dengan nilai yang diberikan oleh manufaktur tidak jauh berbeda dimana besar flow rate dalam cubic feet per minute yang didistribusikan tidak terlalu besar dalam simulasi, sehingga keberadaan outlet mempengaruhi pada keluarnya udara karena udara yang masuk ke ruangan jumlahnya tetap. Tetapi pada kondisi nyata hal tersebut bisa diatasi dengan menggunakan air purifier yang memiliki nilai CADR yang memadai, yang nilainya harus diatas nilai laju ventilasi minimum untuk bernapas dari luar ruang yang ditentukan dalam standar ASHRAE 62-2001.

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The need for clean air is a must in the classroom, especially in the post-pandemic era. Therefore, it is necessary to simulate the flow rate in the class given the air purifier with the aim of seeing the distribution and distribution of air flow in the classroom. The simulation in ANSYS CFX 2019 is based on a 3D Model created accordingly to the actual geometry measurements. The simulation is carried out with class limitations on the flow rate variation for K.101. The measured results are in the form of graphs along with visuals of the Age of Air and Velocity in form of contours and vectors obtained from coordinate points scattered in the class. From the graph, it is shown that there is a tendency to increase the Age of Air value along with the decrease in the flow rate in cubic feet per minute at all coordinate points. In addition to flow rate, the availability of outlets as one of the release points for air affects Age of Air and Velocity. In Velocity vectors, there is air exchange indicated by the direction of the air in window openings and in doorways. This proves the circulation of fresh air is supplied to the room. The difference in flow rate between the data using the value of 5 Air Changes per Hour and the value given by the manufacturer is not much different where the flow rate in cubic feet per minute distributed is not too large in the simulation, so that the presence of outlets affects the exit of air due to the incoming air. to a fixed number of rooms. But in real conditions this can be overcome by using an air purifier that has an adequate CADR value, the value of which must be above the minimum ventilation rate value for breathing from outside the space specified in the ASHRAE 62-2001 standard."

"Hubungan manusia dan sumberdaya air penting dan saling mempengaruhi satu sama lain. Salah satu peristiwa yang perlu mendapat perhatian adalah kontaminasi air tanah melalui dinding sungai. Makalah skripsi ini mengusulkan suatu protokol untuk memodelkan kejadian tersebut menggunakan seepage tank. Pemodelan ini meliputi aliran air melalui media berpori pada kondisi steady dan unsteady serta transpor pencemar mekanisme adveksi-dispersi yang terjadi akibat point-source loading. Meski demikian, terdapat kekurangan dalam analisa hasil pemodelan ini sehingga dibutuhkan pengembangan yang lebih lanjut.

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There is a reciprocal interaction between human and groundwater resources in which all components influence each other. Contamination occurred along soilwater interface in a river is an issue that has to be examined. Physical model of flow through porous media and contaminant transport using seepage tank is proposed to help the understanding of the phenomena. This model describes the flow of water through porous media in steady and unsteady condition and also transport of contaminant in advection-dispersion mechanism that happens for point-source loading. Yet, more development is needed to complete the analysis of this model?s output."

"ABSTRAKData statistik ketenagalistrikan pada tahun 2018 menyebutkan bahwa, masih terdapat masyarakat Indonesia yang belum mendapatkan akses khususnya provinsi Nusa Tenggara Timur yang masih bernilai 61.9%. Tidak tersedianya akses distribusi akibat mahalnya biaya instalasinya dan sulitnya akses menuju lokasi. Oleh karena itu, pembangkit listrik mandiri berbahan baku renewable energy merupakan solusi yang tepat untuk mengatasi krisis energi di daerah terpencil di Indonesia. Disamping itu, potensi energi air di Indonesia mempunyai total potensi sebesar 75 GW. Ini menjadi dasar dari beberapa hasil kajian, turbin pikohidro merupakan solusi yang tepat untuk meningkatkan rasio elektrifikasi di daerah terpencil. Tujuan dalam studi ini adalah memverifikasi fenomena aliran yang terdapat pada sudu turbin piko hidro jenis cross flow pada CFD berdasarkan metode eksperimen Particle Image Velocimetry. Simulasi akan menggunakan ANSYS Fluent 18.1 dengan fitur steady dengan tinggi jatuh air sebesar 1.4 m dan debit aliran 0.01167 m3/s. Ukuran timestep yang digunakan adalah 0.002. Metode eksperimen menggunakan Particle Image Velocimetry dengan Dantec Dynamic laser system. Hasil komputasi divalidasi dengan metode PIV, ditunjukkan oleh distribusi kecepatan pada nosel dan fenomena separasi fluida yang terjadi pada bagian raner turbin arus lintang. Studi ini, menyimpulkan bahwa fenomena pada kondisi sebenarnya dapat digambarkan oleh metode Particle Image Velocimetry dengan proporsi seeding particle dengan diameter maksimum 100 micron.

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ABSTRACT

Based on electricity data in 2018, there are still Indonesian people who do not have access to electricity by 2% (Indonesia). As many as 2% of people who have not received electricity are in remote areas. This is due to the unavailability of distribution access due to the very high installation costs and access to difficult locations. Thus, an independent power plant made from renewable energy is the right solution to overcome the energy crisis in remote areas in Indonesia. furthermore, the potential of water energy in Indonesia has a total potential of 75 GW. This is the basis of several studies, pico hydro turbines are the right solution to increase the electrification ratio in remote areas (Diah; Sarasa; Sari). The purpose of this study is to verify the flow phenomena contained in the crossflow turbine blades on CFD based on the Particle Image Velocimetry experimental method. The simulation will use ANSYS Fluent 18.1 with the steady feature with a head of 1.4 m and a flow rate of 0.01167 m3/ s. The timestep size used is 0.002. The experimental method uses Particle Image Velocimetry with the Dantec Dynamic laser system. The results of computation are then validated by the PIV method, shown by the velocity distribution in the nozzle and the flow phenomenon in the crossflow turbine runner section. This study concludes that the phenomenon of actual conditions can be described by the Particle Image Velocimetry method with the proportion of seeding particles with a maximum diameter of 100 microns.

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