On one method of numerical modeling of piezoconductive processes of a two-phase fluid system in a fractured-porous reservoir

A method of numerical modeling based on splitting by physical processes of two-phase fluid transfer in a formation with fractured-porous reservoirs is described. Reservoirs of this type have a natural fracture system and are described by the dual porosity model. A four-block mathematical model of the fluid redistribution between a pore-type matrix and a natural fracturing pattern is proposed and studied. The resulting system is complex and entails a number of difficulties associated with a large number of variables and the absence of important properties of a linearized system of equations, such as self-adjointness and symmetry, which are present in the description of piezoconductive processes. The complete splitting by physical processes is carried out to solve this problem. The resulting split model is differentially equivalent to the discrete initial balance equations of the system (conservation of the mass components of the fluids and the total energy of the system), written in divergent form. This approach is associated with a nonlinear approximation of the grid functions in time, which depends on the fraction of the volume occupied by the fluids in the pores, and is easy to implement.

An Overview on Bonded Marine Hoses for Sustainable Fluid Transfer and (Un)Loading Operations via Floating Offshore Structures (FOS)

Due to the demand for oil production in varying water depth regions, the advantage of flexible buoyant conduits has led to an increase in bonded marine hoses for fluid transfer and (un)loading operations. The fluid transfer system for bonded marine hoses is dependent on floating offshore structures (FOS). This paper presents an overview of different systems for sustainable fluid transfer and (un)loading operations via FOS, such as Single Point Mooring (SPM) systems. SPMs are component aspects of the techno-economic design and FOS operation. This review aims to present sustainable fluid transfer technologies while addressing the subject of bonded marine hoses based on application, configuration, test models, hose selection criteria, hose-mooring configurations and operational views. This paper also includes an overview of the hose dynamics, with the loading and unloading (or discharging) techniques for sustainable fluid transfer via marine bonded hoses, based on operational challenges encountered. To dynamically present the hose performance in this review, an overview of the test methods’ guidance as specified in available industry standards was conducted. The pros and cons of marine hose application were also presented. Finally, this study presents different marine hose types and novel design configurations applied in implementing hose-mooring systems. Some concluding remarks with recommended solutions on the technology were presented in this review.

4D Investigation of Vortex Fluid Motion Inside the Eyeball

The eye is a complex system of boundaries and fluids with different viscosities within the boundaries. At present, there are no experimental possibilities to thoroughly observe the dynamic 4D processes after one or another method of eye treatment is applied. The complexity of cumulative, i.e., focusing, and dissipative, i.e., scattering, convective and diffusion 4D fluxes of fluids in the eye requires 4D analytical and numerical models of fluid transfer in the human eyeball to be developed. The purpose of the study was to develop and then verify a numerical model of 4D cumulative-dissipative processes of fluid transfer in the eyeball. The study was the first to numerically evaluate the values of the characteristic time of the drug substance in the vitreous cavity until it is completely washed out, depending on the injection site; to visualize the paths of the vortex motion of the drug in the vitreous cavity; to determine the main parameters of the 4D fluid flows of the medicinal substance in the vitreous cavity, depending on the presence or absence of vitreous detachment from the wall of the posterior chamber of the eye. The results obtained are verified by the experimental data available to doctors. In the eye, as a partially open cumulative-dissipative system, Euler regions with high rates of cumulative flows and regions with low speeds or stagnant Lagrange flow zones are defined

Challenges of numerical modelling and simulation of flow inside the hydraulic tank

The basic purpose of the hydraulic tank is to hold a volume of fluid, transfer heat from the system, allow solid contaminants to settle and facilitate the release of air and moisture from the fluid. To perform these important tasks more efficiently, the tank must be properly dimensioned and it must operate in correct flow rate range. At high flow rates it can be subjected to effects of turbulence, leading to poorer performance of the tank. To predict turbulent effects correctly a numerical simulation, based on RANS approach is prepared and run. Difference between k-ε model and k-ω Shear Stress Transport (SST) is investigated and results are presented. Impact of choice of turbulence model is discussed.

Flow conditions inside a small hydraulic tank at excessive flow rates

The basic purpose of a hydraulic tank is to hold a volume of fluid, transfer heat from the system, allow solid contaminants to settle and facilitate the release of air and moisture from the fluid. To perform these important tasks more efficiently, the tank must be dimensioned properly. Above all, it must have an appropriate size. If the tank is too small the flow conditions inside the tank deteriorate, resulting in inadequate conditioning of the hydraulic fluid. Based on the simulation, the paper presents the difference in the change of flow conditions in the case of adequate and insufficient tank sizes. A small industrial hydraulic tank with a capacity of 30 litres filled with hydraulic mineral oil was used as the example of the study.

Vibration Analysis of a Piezoelectric Ultrasonic Atomizer to Control Atomization Rate

In this work, a mechanical vibrational analysis of an ultrasonic atomizer is carried out to control its atomization mass transfer rate. An ultrasonic atomizer is a device constructed with a piezoelectric ring coupled to a metallic circular thin plate with micro-apertures. The mechanism of mass transfer by atomization is a complex phenomenon to model because of the coupling effect between the fluid transfer and dynamic mechanics controlled by a piezoelectric vibrating ring element. Here, the effect of the micro-apertures shape of the meshed thin plate coupled to a piezoelectric ring during vibration, as well as the resonance frequency modes, are numerically studied using a finite element analysis and compared with theoretical and experimental results. Good correlations between the predicted and experimental results of the resonant frequencies and atomization rates were found.

Recovery of radial-axial velocity in axisymmetric swirling flows of a viscous incompressible fluid in the Lagrangian consideration of vorticity evolution

Swirling laminar axisymmetric flows of viscous incompressible fluids in a potential field of body forces are considered. The study of flows is carried out in a cylindrical coordinate system. In the flows, the regions in which the axial derivative of the circumferential velocity cannot take on zero value in some open neighborhood (essentially swirling flows) and the regions in which this derivative is equal to zero (the region with layered swirl) are considered separately. It is shown that a well-known method (the method of viscous vortex domains) developed for non-swirling flows can be used for regions with layered swirling. For substantially swirling flows, a formula is obtained for calculating the radial-axial velocity of an imaginary fluid through the circumferential vorticity component, the circumferential circulation of a real fluid, and the partial derivatives of these functions. The particles of this imaginary fluid “transfer” vortex tubes of the radial-axial vorticity component while maintaining the intensity of these tubes, and also “transfer” the circumferential circulation and the product of the circular vorticity component by some function of the distance to the axis of symmetry. A non-integral method for reconstructing the velocity field from the vorticity field is proposed. It is reduced to solving a system of linear algebraic equations in two variables. The obtained result is proposed to be used to extend the method of viscous vortex domains to swirling axisymmetric flows.

Analysis of Capillary Driven Flows Through Open Microchannels for Biosensing Application

Integrated micro-biosensors and microfluidic systems have been recently used for detection of cells, proteins, and other biomarkers for a wide range of applications. In this work, open micro-channel flows driven by capillary force designed for food safety applications are studied. The micro-channels are used to deliver the nutrients (extracts of different fresh produce) to the sensing site where pathogens reside. The presence of nutrients, simulating the condition that micro-organisms experience in real food materials, allow us to investigate their behavior in real time. Open channels studied in this work are partially covered to allow for etching of the sacrificial layer that creates the channel and use of capillary force to create a self-driven microfluidic system in which fluid flow is actuated by surface tension and wall adhesion. Numerical simulations are used to investigate the fluid flow regime in micro-channels using ANSYS FLUENT. The volume of fraction (VOF) method is used to simulate the dynamics of fluid flow in microchannels made of polycrystalline silicon with a thin layer coating of native silicon dioxide. The effects of channel size and different geometries (open channel, T-junction, and L-junction) on a flow rate of water in the channel are investigated. Our study shows that adding T- and L-junctions to the flow path would create a small delay in the fluid flow in the channel, and the number of junctions directly affect the delay, however, it does not prevent the fluid transfer by capillary force. The (partially covered) open channel geometry presented in this work is compatible with conventional surface micromachining process.

Pengaruh Harmonisa Penggerak Kecepatan Variabel terhadap Kinerja Motor DC FanTest Set

ABSTRAKFan test set merupakan salah satu peralatan penting laboratorium di Jurusan Teknik Konversi Energi yang digunakan untuk menguji karakteristik laju perpindahan fluida. Alat ini terdiri dari gandengan motor DC penguatan bebas dan kipas. Fan test set ini dapat menghasilkan aliran udara yang tetap atau berubahubah dengan menetapkan atau mengubah-ubah kecepatan putaran kipasnya. Kecepatan putaran kipas ini sendiri diatur melalui kecepatan putaran motor dc penggeraknya. Dalam kegiatan penelitian ini telah dilakukan perancangan dan pembuatan konverter ac/dc terkendali yang dapat mengubah daya listrik arus ac menjadi daya listrik arus dc yang dapat dikendalikan. Daya listrik dc variabel yang dihasilkan selanjutnya digunakan untuk menyuplai belitan jangkar motor dc agar kecepatan putaran kipas dan aliran udara dapat dikendalikan. Perangkat ini dapat menghasilkan tegangan keluaran dalam rentang 10 – 100 V dc yang mampu memutar motor dc dari 203,6 – 1849 rpm dan menghasilkan harmonisa yang sebesar 6,7% saat vibrasi motor mencapai 2,8 mm/s.Kata kunci: beban nol, fan test set, harmonisa, konverter ac/dc ABSTRACTFan test set is one of the important laboratory equipment in the Department of Energy Conversion Engineering which is used to test the characteristics of the fluid transfer rate. It consists of a coupled free-amplifying DC motor and fan. This fan test set can produce a fixed or changing airflow by setting or varying the fan speed. The rotational speed of the fan itself is regulated through the rotational speed of the dc motor driving it. In this research activity, the design and manufacture of a controlled ac/dc converter that can convert ac into controllable dc power has been carried out. The resulting variable dc power is then used to supply the DC motor anchor winding so that the fan rotation speed and air flow can be controlled. This device can produce an output voltage in the range of 10 - 100 V dc which is capable of rotating a dc motor from 203.6 - 1849 rpm and producing a harmonic of 6.7% when the motor vibration reaches 2.8 mm / s.Keywords: no load, fan test set, harmonics, ac/dc converter