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"The study of hydrodynamic stability is fundamental to many subjects, ranging from geophysics and meteorology through to engineering design. This treatise covers both classical and modern aspects of the subject, systematically developing it from the simplest physical problems, then progressing to the most complex, considering linear and nonlinear situations, and analyzing temporal and spatial stability. The authors examine each problem both analytically and numerically. Many relevant fluid flows are treated, including those where the fluid may be compressible, or those from geophysics, or those that require salient geometries for description. Details of initial-value problems are explored equally with those of stability. The text includes copious illustrations and an extensive bibliography, making it suitable for courses on hydrodynamic stability or as an authoritative reference for researchers. In this second edition the opportunity has been taken to update the text and, most importantly, provide solutions to the numerous extended exercises."

"Hidrodinamika merupakan salah satu faktor yang mempengaruhi pertumbuhan mikroalga. Dua parameter hidrodinamika yaitu kecepatan superfisial (UG) dan Retention Time Distribution (RTD) setelah direview dari hasil penelitian sebelumnya, tidak dapat digunakan sebagai basis scale up. Dua parameter lainnya yaitu gas holdup (ε) dan koefisien perpindahan massa (kLa) diujicobakan. Pada kondisi operasi iso-ε dan iso-kLa terhadap acuan, pengujian produksi biomassa Chlorella vulgaris Buitenzorg dilakukan pada volume 18 L (acuan) dan 40 L. Hasil penelitian menunjukkan bahwa pertumbuhan pada kondisi iso-ε relatif paling sama dengan acuan. Parameter gas holdup (ε) merupakan parameter hidrodinamika yang bisa menjadi basis scale up

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Hydrodynamic is one factor that influences microalgae grwoth. Two hydrodynamic parameter, superficial velocity (UG) and Retention Time Distribution (RTD), after reviewed from the last research, they can?t used as scale up basis. Another parameter, gas holdup (ε) and mass transfer coefficient (kLa), trial tested then. In operation condition which iso-ε and iso-kLa respect to reference, a test of Chlorella vulgaris Buitenzorg biomass production has been done in two reactor volume, 18 L (reference) and 40 L. The result shows that the microalgae growth in iso-ε condition is more similar relatively with the reference. It?s mean that gas holdup (ε) parameter can be used as scale up basis."

"Dalam penelitian ini dilakukan penggabungan dua metode Proses Oksidasi Lanjut yaitu metode ozonasi dan kavitasi hidrodinamika dengan menggunakan pelat berlubang untuk Pengolahan limbah fenol sintetik. Penggabungan dua metode ini bertujuan untuk melihat seberapa signifikan pengaruh penggabungan kedua metode ini dibandingkan dengan kedua metode tersebut diaplikasikan secara terpisah. Untuk mencapai tujuan tersebut, dilakukan tiga variasi proses yaitu metode ozonasi, kavitasi hidrodinamika, dan gabungan keduanya. Selain itu, dilakukan pula variasi terhadap laju alir sirkulasi, dosis ozon, dan pH untuk mendapatkan kondisi yang optimal dalam penyisihan limbah fenol. Pada penelitian ini terbukti bahwa penyisihan fenol dengan metode gabungan teknik ozonasi dan kavitasi hidrodinamika menggunakan pelat berlubang dengan kondisi operasi laju alir sirkulasi terbaik yaitu 6 LPM, dosis ozon dengan dua ozonator, dan pH tinggi meghasilkan persentase penyisihan yang lebih baik mencapai 81,4 % dibandingkan dengan metode ozonasi sebesar 69,8 %, dan kavitasi hidrodinamika sebesar 22,1 %.

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In this research, carried out the merger of two Advanced Oxidation Process methods, namely ozonation technique and hydrodynamic cavitation by using orifice plate to degrade synthetic phenol. This combination method is carried out to see how significant the effect of the merger of these two methods compared with both methods applied separately. To achieve that purpose, carried out three variations of the process, there are ozonation technique, hydrodynamic cavitation, dan merger of both method. Moreover, also conducted a variation of the flow rate of circulation, ozone dosage, and pH to obtain optimal operating conditions in the phenol waste treatment. Proven in this research that phenol degradation using the combination method of ozonation technique and hydrodynamic cavitation using orifice plate with operating conditions of 6 LPM circulation flow rate, two source of ozone, and basic environment produces better result reaching to 81,4 % phenol degraded compared to ozonation technique 69,8 %, and hydrodynamic cavitation 22,1 %."

"Hydrodynamic charactersitic for the mixing of gas-solid-liquid in membrane bioreactor submerged (MBRs) and its influence on mass transfer was studied computationally at various solid concentration, incoming gas rate and the befle distance

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"Penelitian ini ditujukan untuk mengevaluasi kinerja rangkaian alat desinfeksi gabungan ozonasi dan kavitasi hidrodinamika terhadap bakteri Escherichia coli. Dosis ozon dan laju alir sirkulasi limbah air tercemar bakteri Escherichia coli digunakan sebagai variabel penelitian untuk mengetahui kondisi terbaik kombinasi metode-metode tersebut. Variasi laju alir limbah dilakukana pada 4 ; 5,5; 7 LPM sedangkan dosis ozon divariasikan dengan penggunaan ozonator komersial rumah tangga mulai dari 1 84,38 mg/jam , 2 157,44 mg/jam dan 3 231,36 mg/jam unit ozonator.Hasil desinfeksi menunjukan penurunan lebih baik untuk setiap kenaikan laju alir air sirkulasi serta kenaikan dosis ozon. Metode terbaik merupakan metode gabungan kavitasi hidrodinamika pada 7 LPM dan ozonasi dengan dosis 231,36 mg/jam dengan waktu operasi selama 60 menit yang mampu menurunkan konsentrasi bakteri Escherichia coli sampai 17 CFU/mL untuk konsentrasi awal 8,4 x 105, 0 CFU/mL untuk konsentrasi awal 9,7 x 104, dan 0 CFU/mL untuk konsentrasi awal 8,3 x 103 . Kata kunci : desinfeksi, Eschericia coli, ozon, ozonasi, kavitasi hidrodinamika.

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This research aimed to evaluate the performance of a series of combined ozonation disinfection unit and hydrodynamic cavitation in the disinfection of Escherichia coli bacteria. Ozone dose and the circulation flow rate of wastewater contaminated with the Escherichia coli is used as variables of research to determine the best conditions of the combination methods. Variations of waste flow rate are 4 5.5 and 7 LPM, while ozone dosage is varied by using household commercial ozonator ranging from 1 84,38 mg h , 2 157,44 mg h and 3 231,36 mg h unit of ozonator.

The best result of decreasing the Escherichia coli bacteria concentration was obtained by combining method of disinfection by hydrodynamic cavitation at 7 LPM and ozonation from 3 units ozonator with 231.36 mg h of ozone dosage for 60 minutes of desinfection are 17 CFU mL final concentration from 8.4 x 105, 0 CFU mL for initial concentration 9,7 x 104 CFU mL, and 0 CFU mL for initial concentration 8,3 x 103 CFU mL. Keywords disinfection, Eschericia coli, ozone, ozonation, hydrodynamic cavitaion."

"Penelitian ini dilakukan untuk mengetahui perbandingan performa mesin flotasi self aerating vs induced air dengan efek penambahan variasi dosis SiBX terhadap recovery Cu dan Au, sehingga dapat dilakukan optimalisasi proses recovery Cu dan Au di PT. X Papua.Penelitian dilakukan dalam skala plant concentrator C1, digunakan tiga jenis variasi dosis SiBX, yaitu 5 g/t, 10 g/t, dan 15 g/t yang diterapkan pada kedua jenis mesin flotasi. Selanjutnya dilakukan pengujian assay mineral dan XRD. Hasil recovery Cu dan Au secara keseluruhan menunjukkan mesin flotasi self aerating mampu mengangkat Cu dan Au lebih efektif daripada mesin flotasi induced air pada semua fraksi ukuran mineral coarse, medium, dan fine. Recovery Cu dan Au dipengaruhi sifat hydrodynamic dari kedua jenis mesin. Efek penambahan variasi dosis SiBX kurang signifikan terhadap recovery Cu dan Au sehingga perlu dilakukan penelitian lebih lanjut.

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This research had been done to know the performance of self aerating vs induced air flotation machine with variation of SiBX dosage to Cu and Au recovery, so the recovery of Cu and Au at PT. X Papua can be optimized. Three variations of SiBX dosage 5 g T, 10 g T, and 15 g T are used for both flotation machines at flotation circuits.XRD and minerals assay were conducted and show self aerating flotation machine has a higher Cu and Au recovery than induced air flotation machine at all fraction size, coarse, medium, and fine. Hydrodynamic characterization influenced the result of Cu and Au recovery. It was evaluated that the effect of SiBX dosage addition could not be seen clearly, so it is necessary to do next level of research, in order to see the effect of SiBX addition to Cu and Au recovery."

"Energi gelombang laut memiliki potensi energi terbaharukan yang besar, dan studi ini mencoba untuk memanfaatkan energi terbaharukan dengan menggunakan suatu floating absorbers yang dipasangkan dengan peralatan Sistem hidrolik Power Take-Off (PTO). Studi ini memfokuskan pada analisis hidrodinamika yang terjadi apda badan floating absorbers dengan mengaplikasan potential flow theory dengan metode Constant Panel Method dan Higher Order Boundary Element Method dan evaluasi dari pengaruh dari berbagai rasio diameter terhadap draft. Setelah itu, studi ini akan menganalisis RAOs (Response Amplitude Operators) dan gaya hidrodinamika untuk berbagai rasio untuk menentukan desain optimal. Dari hasil analisis, didapatkan rasio optimal untuk floating absorber adalah 1.0 dengan mempertimbangkan keadaan gelombang.

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Ocean wave energy has a large potential for renewable energy, and this study attempts to utilize renewable energy by using a floating absorber coupled with a hydraulic Power Take-Off (PTO) system. This study focuses on hydrodynamic analysis that occurs in floating absorber bodies by applying potential flow theory with the Constant Panel Method and Higher Order Boundary Element Method and evaluating the effect of various diameter ratios on draft. After that, this study will analyze the RAOs (Response Amplitude Operators) and hydrodynamic forces for various ratios to determine the optimal design. From the analysis results, the optimal ratio for floating absorber is around 1.0 based on the condition of the waves."

"Telah dilaporkan bahwa kinerja pengolahan di kolam fakultatif di Instalasi Pengolahan Air Kotor (IPAK) Bojongsoang adalah tidak stabil. Salah satu penyebabnya adalah karakteristik hidrodinamika yang tidak sesuai dengan criteria. Yang termasuk dalam karakteristik hidrodinamika yang tidak tepat antara lain kehadiran daerah mati, aliran pendek, dan turbulensi oleh arus eddy. Penelitian ini bertujuan untuk menganalisa pengaruh variasi debit influen terhadap karakteristik hidrodinamika menggunakan model matematis. Model hidrodinamika dua dimensi dibangun dari dua persamaan hidrodinamika, yaitu persamaan kontinuitas dan persamaan momentum. Kedua persamaan diselesaikan dengan metoda numerik beda hingga semi implisit (Crank-Nicolson). Dari hasil simulasi, dianalisa nilai bilangan Froude aliran serta waktu tinggal efektif dan luas efektif kolam fakultatif untuk melihat kehadiran daerah mati.Hasil simulasi menunjukkan bahwa daerah mati terdapat di tengah kolam. Apabila debit influen semakin besar, waktu tinggal efektif dan luas efektif semakin besar. Selain itu, distribusi nilai bilangan Froude menunjukkan bahwa nilai 10-10 semakin berkurang bila debit influen semakin besar. Dapat dikatakan bahwa daerah mati akan berkurang pada debit influen yang lebih besar. Dengan demikian debit influen yang semakin besar akan memperbaiki karakteristik hidrodinamika di kolam fakultatif.

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The Effects of Influent Debit on Hydrodynamic Characteristic of Bojongsoang Facultative Pond: Without Wind Effects. The performance of facultative pond in Bojongsoang WWTP have reported to be unstable. One of the cause of the unstable performance is the hydrodynamic characteristics that not met the criterion. The improper hydrodynamic characteristics are included the existence of dead-zone, the short-circuiting, and the turbulence due to eddy current. The study was to analyze the effect of the influent debit variation on the hydrodynamic characteristics of the pond using mathematical model. The two-dimensional hydrodynamic model was built from two hydrodynamic equations which are continuity and momentum equations. The equations were solved by finite-difference numerical method of semi-implicit (Crank-Nicolson).From the simulation results, the Froude number of the water flow was analyzed. Beside that, the effective residence time and the effective area were calculated. All of them were done to analyzed the existence of the dead-zone in the pond. The simulation results show that the dead-zone was exist in the center of the pond. when the influent debit was larger, the effective residence time and the effective area become larger. The distribution of the Froude number value shows that the area with the value of 10-10 become reduced in the larger influent debit. The existence of the dead-zone was reduced since the influent debit become larger. It can be said that the larger influent debit can improve the hydrodynamic characteristics of the pond."