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The experimental studies on flow pattern of adiabatic gas-liquid two-phase flow in horizontally oriented mini-channel were conducted. The test section was a 1.6 mm inner diameter glass pipe. The range of gas and liquid superficial velocities were 0.025 - 66.3 m/s and 0.033 - 4.935 m/s, respectively. The working fluids were air and glycerol aqua solution in various percentage, 0%, 20%, 40%, and 60% indexed by W, G20, G40, and G60, respectively. The flow pattern data were obtained by analyzing the video images, captured by using the high-speed camera. As a result, it was found that the flow patterns observed in the present study were bubbly, plug, slug-annular, annular, and churn, while the stratified flow was not appeared. In the flow pattern map, the change of liquid viscosity affects to the shift of the transition line between flow pattern, particularly slug-annular to annular and slug-annular and annular to churn flow. [ABSTRACT FROM AUTHOR]

The Liquid hold-up and the Interfacial Friction Factor on the Air-Water Stratified Two-Phase Flow in a Horizontal Pipe have been experimentally investigated using superficial gas and liquid velocity of 4 - 16 m/s and 0.02 to 0.1 m/s, respectively. The stratified flow is observed on the horizontal acrylic pipe with 26 mm inner diameter and 9 m length. This present work has utilized the various methods of observation: visual observation through high speed video camera, hold up measurement by using CECM, and pressure gradient analysis which is gathered from the Validyne pressure transducer. The pressure gradient and liquid hold-up signal are sent through amplifier than converted into digital signal by Analog to Digital Converter (ADC). As a result, the characteristics of stratified flow is successfully revealed. Furthermore, a new correlation for hold-up which is based on the gas and liquid superficial velocity, and Froude number is proposed. The R2 which reaches 0.971 and the small value of error band (around 30 %) shows that the proposed correlation produce a good performance. Similarly, a new correlation for interfacial friction factor is also proposed which is arranged as a function of liquid hold-up, gas, and liquid Reynolds number. It produces a satisfying performance which is proven by the high value of R2, 0.999. Moreover, the error band between the proposed correlation and the experimental data is quite small, around 5 % on most of all data. [ABSTRACT FROM AUTHOR]

The research investigates the possible effects on the reclamation project in Jakarta Bay which is located in the north of Jakarta, the capital city of Indonesia. The concept of rearranging the north Jakarta coast includes the concept of reclamation 17 islands. The impact of the reclamation project may increase the sedimentation in the river mouth and may degrade the ecosystem and environment quality its vicinity. The bay is a shallow water area with an average depth of 15m. In the research, sediment distribution is simulated using several parameters: surface water level, water depth, precipitation rate, and river discharge from five rivers which feed the sediment and fresh water to the bay. The simulation is developed in order to examine the condition of the bay before and after the reclamation project. The research attempts to reveal the inter-correlation between the tidal current, river discharge, and the cohesive sediment in the bay. The hydrodynamics simulation before the reclamation project was run for 31 days in the month of January (wet season) and September (dry season) in the year of 2011. The simulation after the reclamation project was run for 29 days in February (wet season) and May (dry season) 2016. Based on the research, the movement of sediments is dominantly influenced by the tidal current instead of the precipitation and river discharge. The research also revealed a high turbidity level near the river mouth particularly in Cengkareng River. The erosion and sedimentation rate tend to the increase the loads from the catchment areas. However at the same time, the erosion in other areas is increased as a result of the development on the coast of Jakarta Bay. [ABSTRACT FROM AUTHOR]

Void fraction is an important parameter in two-phase flow. In the present work, the adiabatic two-phase airwater flow void fraction in a horizontal minichannel has been studied experimentally. A transparent circular channel with 1.6 mm inner diameter was employed as the test section. Superficial gas and liquid velocities were varied in the range of 0.025 - 66.3 m/s and 0.033 - 4.935 m/s, respectively. Void fraction data were obtained by analyzing the flow images being captured by using a high-speed camera. Here, the homogeneous (β) and the measured void fractions (ε), respectively, were compared to the existing correlations. It was found that: (1) for the bubbly and slug flows, the void fractions increases with the increase of JG, (2) for churn, slug-annular, and annular flow patterns, there is no specific correlation between JG and void fraction was observed due to effect of the slip between gas and liquid, and (3) whilst for bubbly and slug flows the void fractions are close to homogeneous line, for churn, annular, and slug-annular flows are far below the homogeneous line. It indicates that the slip ratios for the second group of flow patterns are higher than unity. [ABSTRACT FROM AUTHOR]

Research on the T-junction is still underway for the flow of liquid-liquid (kerosene-water). Some research on the characteristics of kerosene-water separation was performed using T-junction oriented upward branch with a 60° angle. To observe the effect of diameters ratio on the phase separation that produced T-junction then made a test section with a horizontal pipe diameter 36 mm, while the side arm 36 mm diameter, 26 mm and 19 mm (diameters ratio of 1, 0.7 and 0.5) by using plexiglass pipe type. Based on experimental results and visualization of data flow in the test section, to the value obtained 60% water cut, the maximum separation efficiency of 94%, FK = 0.94 and FW = 0.001 with a diameter ratio of 1. For other diameter ratio of 0.7 and 0.5 respectively separation efficiency of 66%, FK = 1 and Fw = 0.34 for 0.7 and separation efficiency of 84%, FK = 1 and Fw = 0.16 for 0.5, the best value is obtained at a water cut 60% too. All the best conditions to achieve the above-stratified flow pattern. [ABSTRACT FROM AUTHOR]

On the Chinese Loess Plateau many hydraulic parameters related to soil erosion are highly variable and often cross-correlated. Hillslope-gully side erosion systems are widespread on the Loess Plateau, but the quantification between the hydraulic parameters is still unknown for the system. A constant headwater scouring experiment in the laboratory was performed in this study and combined a model with two slope segments (with hillslope and gully sides). Five inflow rates of 6, 8, 10, 12 and 14 L/min were used. Some hydraulic parameters (the flow velocity, shear stress, unit stream power, Reynolds Number, Froude Number, Darcy-Weisbach friction factor, and Manning coefficient) were analysed. Regression equations were developed for the parameters. The results provide a basis for in-depth research regarding the erosion processes of hillslope-gully side erosion systems. [ABSTRACT FROM AUTHOR]

The article discusses research which investigated the excitation period effects on two-dimensional (2D) liquid sloshing by Moving Particle Semi-Implicit (MPS) method. Topics discussed include the comparison of flow pattern and impact pressure with experimental data for validation and four types of sloshing waves observed for different excitation periods.

Low-Rate Denial of Service (LDoS) attack has been a hot topic in network security area in the last decade. LDoS flows are affected by the dynamical environment of the Internet, making it difficult to understand the behaviors of LDoS flows at the receiver side. In this paper, we studied the impact of end-to-end delay on LDoS flows in order to provide a foundation for detecting and defense of LDoS attacks. We gathered data of LDoS flows from the Internet and analyzed their traffic patterns. The experimental results have shown that end-to-end delays can distort LDoS flows greatly although they are sent in regular patterns. [ABSTRACT FROM PUBLISHER]

A non-invasive measurement method of visualizing the flow pattern and charge distribution of gas-solid two-phase flow has been applied to flow measurement in a gravity-dropping conveyance system and a pneumatic conveyance system. The permittivity distribution acquired from an ECT (Electrical Capacitance Tomography) can be used to improve the iteration accuracy in establishing charge sensitivity field of an EST (Electrostatic Tomography), hence to reduce the uncertainty of inverse calculation of charge distribution. The experimental results show that, for the gravity-dropping system, charge density increases with particle concentration, whilst in the pneumatic conveyance system, charge density decreases in the area where the particle concentration is higher. The total charge intensity decreases with the increase of the concentration of pulverized coal in the pipe. [ABSTRACT FROM PUBLISHER]

The article discusses a study that investigates the dynamic characteristics of flow past two unequal cylinders in tandem configuration based on numerical and experimental simulation. The characteristic flow patterns based on the time-averaged flow field at various center-to-center spacing ratios are established. The relevance of flow around two circular cylinders in tandem configuration to engineering applications that include offshore platforms and bridge piers are also explored.

This study investigated on details of flow characteristics of a compressor with 2-dimensional impeller at various flow rates. Experiment for a low speed compressor model in a water reservoir was performed to analyze the flow field in the vaneless diffuser and volute casing, which was done by PIV measurement. It was also focused on the periodic flow patterns occurring at low flow rate near unstable operating region of the compressor. At low flow rate condition, the flow visualization clearly shows that the flow energy from impeller is highly accumulated at the compressor exit by the blockage effect of a flow damper and consequently the reverse flow occurs in the diffuser. [ABSTRACT FROM AUTHOR]

A series of experiments was conducted to investigate the flow boiling of R141b in hairpin tubes. A focus was addressed on visually observing flow boiling and two-phase flow in U-turn bends of a vertical upward hairpin tube with inner diameter of 6 mm at liquid velocities of 0.098, 0.147 and 0.196 m/s and heat fluxes in the range of 6191 W/m2 to 24763 W/m2, respectively. The bend could break up large vapor slugs in two ways, bubble tail fracture and bubble rupture, which induced significant effects on local heat and mass transfer. Under certain experimental conditions, small bubbles formed in the bend could not coalesce to be large vapor slugs but accumulate to form a unique flow pattern and greatly release thermal non-equilibrium in the rest part of hairpin the tube. [ABSTRACT FROM AUTHOR]

The flow pattern of gas-liquid two-phase flow in an aeration tank is of critical effect upon mass transfer by the convection. Bubble plume provides unsteadily fluctuating two-phase flow during the aeration. This paper the study on the unsteady structure of bubble plume is dealt with from experiment. The time-serial bubble plume images of different cases in tank have been analyzed. The RCC-PIV has been employed to calculate the velocities in those cases, and then the time-serial vortex, the total turbulence intensity, the time-serial streamline are obtained. It has been shown that the aspect ratio and void fraction are the dominant factors influencing the unsteady structure of bubble plume. When the aspect ratio is unity and the void fraction gets higher, the bubble plume has symmetrical vortex structure and longest residence time, which is beneficial for optimizing the aeration system and enhancing the applied range of bubble plume. [ABSTRACT FROM AUTHOR]

The article presents a study which examined experimental flow patterns with factors affecting the characteristics of pressure gradients in horizontal heavy oil-water pipe flows. Factors affecting the pressure gradient characteristics in oil-water pipe flow such as water volume fraction, mixture velocity, temperature and surfactant content are discussed. Typical flow patterns such as emulsion of water in oil (Dw/o) and water flows along the tube wall and Dw/o flows in the center and upper part of the tube are analyzed.

The article provides information on a study which discussed a discrete vortex model (DVM) based on full vortex cloud method, used to stimulate the wave-current flow fields around pile-groups or arrays used in ocean engineering. The simulations of the flow around a circular cylinder and the flow around a pair of circular cylinders in side-by-side arrangement are presented. Flow patterns in wave-current fields are analyzed. The time histories of inline force coefficients of isolated pile and tandem arranged bi-piles are also given.

Due to the complexity of two-phase flow field in jet-pump, it is of difficult to accurately measure in-situ phase fraction in the pump. Electrical resistance tomography (ERT) has been successfully used in predicting gas concentration, dispersed phase velocity and flow regimes in both vertical and horizontal flows. Thus, the present study carried out an experimental investigation of in-situ the phase fraction in a jet-pump using the ERT technique. A new jet-pump with ERT sensors was designed to measure in-situ phase fraction and flow regime. The study was based on laboratory experiments that were carried out on a 50 mm vertical flow rig for various gas and liquid phase superficial velocities. A total of 6 experimental tests were conducted. The flow pattern of gas-liquid in the jet-pump was studied using the ERT technique. Results suggest the flow patterns recognition using ERT systems can not only be applied for most two-phase flow regimes, but also for the visualisation of a complex system. Furthermore, the visualizations of a rapid mixing process in the throat of a jet pump obtained in the present work provide a reliable basis for theoretical study and optimal design of jet pumps. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

In this work the Smoothed Particle Hydrodynamics (SPH) method is used to simulate iron ore pellets flow. A continuum material model describing the yield strength, elastic and plastic parameters for pellets as a granular material is used in the simulations. The most time consuming part in the SPH method is the contact search of neighboring nodes at each time step. In this study, a position code algorithm for the contact search is presented. The cost of contact searching for this algorithm is of the order of Nlog2N, where N is the number of nodes in the system. The SPH-model is used for simulation of iron ore pellets silo flow. A two dimensional axisymmetric model of the silo is used in the simulations. The simulation results are compared with data from an experimental cylindrical silo, where pellets are discharged from a concentric outlet. Primary the flow pattern is compared. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

In the present experimental study cavitation phenomena in both He I and He II flows were investigated through the application of the PIV technique and visual observation under the saturated vapor pressure condition. The cavitation flow was generated in the downstream regions of a Venturi channel and a converging jet nozzle driven by a contracting metal bellows. It is seen that cavitation inception is a kind of stochastic process and has definite temperature dependence. The spatial distribution of the cavitation bubble velocity is measured by using the PIV technique. Some differences in the cavitating flow pattern and the void fraction are found between He II and He I cavitating flows. The PIV result indicates that the void fraction for He II flow is larger than that for He I flow. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]