Begell House Inc.
International Journal of Fluid Mechanics Research
FMR
2152-5102
41
6
2014
Incompressible Smoothed Particle Hydrodynamics Simulations of Fluid-Structure Interaction on Free Surface Flows
471-484
Abdelraheem M.
Aly
Department of Mathematics, Faculty of Science, Abha, King Khalid University, Saudi Arabia;
Department of Mathematics, Faculty of Science, South Valley University, Qena, Egypt
Mitsuteru
Asai
Department of Civil Engineering, Kyushu University 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
In this paper, fluid-structure interaction (FSI) on free surface flows has been simulated using ISPH method. The governing equations are discretized and solved with respect to Lagrangian moving particles filled within the mesh-free computational domain and the pressure was evaluated by solving pressure Poisson equation using a semi-implicit algorithm based on the projection scheme to ensure divergence free velocity field and density invariance conditions. In this study, the structure is taken as a rigid body and it modeled using ISPH method by two different techniques. In the first technique, the solid particles are treated initially as fluid particles and after corrector step in projection method, the solid constraint is applied to get the rigid body motion. In the second technique, we computed the motions of a rigid body by direct integration of fluid pressure at the position of each particle on the body surface. Then, the equations of translational and rotational motions were integrated in time to update the position of the rigid body at each time step. The applicability and efficiency of current ISPH method with the two different treatment of rigid body are tested by comparison with reference experimental results.
An Experimental Analysis through a Stereo-PIV System of an Axial Fan Used in Electronic Equipment
485-498
Francesco
Corvaro
Dipartimento di Ingegneria Industriale e Scienze Matematiche (DIISM), Università
Politecnica delle Marche, Ancona, Italy
Massimo
Paroncini
DIISM, Dipartimento di Ingegneria Industriale e Scienze Matematiche, Università Politecnica delle
Marche, Via Brecce Bianche - 60131 Ancona, ITALY
In the electronic industry, the large request of great device performances needs new and improved cooling system in order to dissipate significant thermal load. The research is often dedicated to study and analyse the characteristics of the existing cooling system such as the axial fans. A lot of numerical studies are performed to describe the convective flow generated by these common devices but in the scientific literature it is hard to find experimental analysis of their dynamic field. This deficiency of experimental data is probably connected with the three-dimensional flow which is produced by this equipment. In this paper the flow, generated by an axial fan, is studied and characterized through the use of a stereo-PIV system. So it is obtained a three-dimensional dynamic field and through the velocity maps the efficiency of the fan could be evaluated in order to its heat transfer capability. In the experimental analyses different rotation velocities of the axial fan are performed and the velocity maps are obtained at different distance from the outlet.
Hydrodynamics Interaction between Air Bubbles and Particles in Flotation Revealed by High-Speed Visualization
499-511
Harinaldi
Department of Mechanical Engineering, Faculty of Engineering, University of Indonesia Kampus UI-Depok, Jawa Barat, 16424, Indonesia
Warjito
Department of Mechanical Engineering, Faculty of Engineering, University of Indonesia Kampus UI-Depok, Jawa Barat, 16424, Indonesia
Manus
Setyantono
Department of Mechanical Engineering, Faculty of Engineering, University of Indonesia Kampus UI-Depok, Jawa Barat, 16424, Indonesia
A mineral separation process usually involves a flotation method which uses buoyancy forces on microbubbles. The important factors which determine the separation efficiency heavily relate to the intensity of occurrence of bubble-particle collision. This occurrence is mainly controlled by the hydrodynamics interaction between the bubbles and mineral particles so that improved understandings on the underlying physics become the key point in improving the performance of separation process. In the present research the interaction between bubble and particles without interfacial modification is studied experimentally focusing on the mode of interaction, probability of collision and the angle of detachment. The test was done by using the experimental set up which consisted of a fluid container made of glass, syringe pump as bubble generator, particle feeder, illumination system, high speed video camera and image processing software. The bubble generator and particle feeder were carefully designed so that the bubble formation, as well as the particle feeding could be precisely controlled and water was used as the medium. The microhydrodynamics aspects which were observed and analyzed included the collision, attachment, detachment and particles movements. The results show that two modes subprocesses after the bubble-particles collisions characterized the microhydrodynamics interactions between particle and bubble namely reflection and attachment with the former dominates the mechanism with higher probability of occurrence. Moreover, larger particles are influenced by the microhydrodynamics forces when they are below the bubbles which are floating upward. The collision efficiency is then influenced by the particles velocity toward the bubble within a very small distance. Here, the particles movement is affected by a fore- and aft-asymmetric motion of the fluid surrounding the bubbles. Further, the particles movement depends on the mobility of bubble surface and particles inertia.
Similarity Problems for Steady State Geothermal Systems
512-525
Olga
Kordas
KTH − Royal Institute of Technology Teknikringen, 34, SE-10044, Stockholm, Sweden
Eugene
Nikiforovich
Institute of Hydromechanics of National Academy of Sciences of Ukraine 8/4, Zhelyabov St., 03680, Kyiv-180, MSP, Ukraine
Increasing energy efficiency of the geothermal systems (GS) is an important task for further development and implementation of the geothermal energy for industrial and domestic heating and cooling. Achieving the higher efficiency, in its turn, requires insight into thermodynamic interaction of all elements of GS. Mathematical modeling of such systems, as well as the development of similarity methods for such modeling is highly relevant because of the high cost of the GS. The presented in the paper mathematical model of a strongly non-equilibrium thermodynamic systems Ground−Borehole Heat Exchanger−Ground Source Heat Pump has been elaborated to describe the energy exchange between the ground, BHE and GSHP. Based on this model a stationary problem of such system operation has been solved. A new type of non-equilibrium spatial scales for this problem, not depending on its geometric parameters and that are determined by energy characteristics of GS are introduced. It is shown that in the special variables considered problem is characterized by a unique dimensionless parameter − the ratio of the thermal conductivity of the ground and brine. This allows us to formulate new approaches to GS modeling. The physical interpretation of the received results is provided.
Falling Film Thickness Measurement Using CFD Analysis over Horizontal Tubes
526-535
Nitin U.
Korde
Department of Mechanical Engineering, G. H. Raisoni Institute of Engineering & Technology Pune 412207, Maharashtra, India
Ashok T.
Pise
Department of Mechanical Engineering, Government College of Engineering Karad 415124, Maharashtra, India
P. S.
Gunavant
Department of Mechanical Engineering, Govt. College of Engineering Karad, 415124, India
The objective of this study is to calculate film thickness of falling film thickness over circular horizontal tubes considering axial effect of flow along the tube using commercial computational fluid dynamics software. Commonly used six fluids are selected for this study, with modified Galileo number Ga* in the range of 36 to 553. Efforts are made to study variation in geometrical parameters i.e. tube diameter and spacing between the tubes. Commercial CFD code (FLUENT version 13.0.0) is used for simulation over two horizontal tubes considering 3D configurations. Model of coupled volume-of-fluid is used for tracking the motion of liquid falling film and air liquid interface. Results obtained are discussed in terms of effect of modified Galileo number Ga* on average film thickness. It is observed that the nature of film thickness over the tubes is similar to available experimental and numerical data. An attempt is made to propose correlation based on numerical study for film thickness in terms of new composite non-dimensional numbers, tube angle and flow rate.
Injection Behaviour of Fractured Reservoirs at Near Wellbore and Far Field Areas − A CFD Study
536-546
Gbenga Folorunso
Oluyemi
School of Engineering, Robert Gordon University Aberdeen, AB10 7GJ, UK
Limniyakul
Kanin
School of Engineering, Robert Gordon University Aberdeen, AB10 7GJ, UK
Arwin
Nair
School of Engineering, Robert Gordon University Aberdeen, AB10 7GJ, UK
Flow partitioning in fractured reservoirs especially during injection and production operations poses a great challenge to the optimisation of these important field operations. For example, flow partitioning into the fracture from the matrix may limit production from a well if the drilling and completion design does not take into consideration the position and intensity of the fracture networks. In the same vein, during chemical injection into a fractured reservoir for remedial flow assurance related purposes, the injected chemical may be forced into fracture zones with relatively low flow resistance depriving the target zones of the much needed dosage of chemical. Though several solution options are available to the operators to solve some of these optimisation problems if known at the planning and design stage of field development, however, there are very few options available to them to evaluate the flow behaviour of their fractured reservoirs at both near wellbore and far field areas of the reservoirs. In this study, we used CFD to investigate the injection behaviour of fractured reservoirs at near wellbore and far field areas of the reservoir in both vertical and horizontal directions under conditions of near equal and widely varying fracture and matrix permeabilities. The results highlight the twin effects of vertical flow distance from the matrix sites to the fracture face and fracture/matrix permeability on pressure distribution and flow partitioning during injection operation. In addition, the results demonstrate the application of CFD as a potential tool for preliminary evaluation and characterization of fractured reservoirs.
Implementation of Velocity and Pressure Non-Equilibrium in Gas-Liquid Two-Phase Flow Computations
547-555
Dia
Zeidan
School of Basic Sciences and Humanities,
German Jordanian University, Amman, Jordan
R.
Touma
Department of Computer Science & Mathematics Lebanese American University Beirut, Lebanon
A.
Slaouti
School of Engineering and Technology, PSB Academy Singapore
A set of fully hyperbolic and fully conservative mixture conservation laws that treat the relative motion in gas-liquid two-phase flows are presented. These laws are based on compressible gas-liquid two-phase flow with velocity and pressure non-equilibrium. The resulting theoretical model accounts for the interaction between the gas and liquid phases with more reasonable physical meaning. Within this framework, the distinctness of the model conservation laws enables a straightforward extension and application of single-phase fluid dynamics numerical methods. Computations for a set of rarefaction waves test problem show that the interfacial friction source term has a strong influence on both the flow parameters and the wave structure in non-equilibrium two-phase flows.
Modeling Study on Fluid Flow in Horizontal Perforated Pipes with Wall Influx
556-566
Quan
Zhang
MOE Key Laboratory of Petroleum Engineering, China University of Petroleum (Beijing) Beijing, PR China
Zhiming
Wang
MOE Key Laboratory of Petroleum Engineering, China University of Petroleum (Beijing) Beijing, PR China
Over the past two decades, the modeling of fluid flow in a perforated pipe with influx through orifices on the pipe wall has been recognized as an important issue especially in the field of horizontal wells. Although several investigators, such as Su, Yuan and Ouyang, etc. have done some modeling studies upon such special variable mass flows, almost all of the models presented are still questionable and inconclusive which implies that additional efforts should be made to get more robust and applicable ones. Based on an thorough theoretical analysis and previous research achievements, an improved model has been developed for the prediction of pressure profiles upon single-phase flow in the horizontal perforated pipes. The new model is then implemented with the use of the Visual Basic.NET package and a distinctive and useful class has been designed in order to solve the proposed model conveniently. A preliminary comparison between the results obtained by the improved model and Su model is also conducted in this paper and the result shows that the new developed model corresponds better to the practical situation. Moreover, the improved model comprehensively represents the various physical phenomena in the horizontal perforated pipe flow with wall mass transfer, such as the unique lubricating effect caused by the fluid influx, and could be easily used to predict the pressure drop of fluid flow in the horizontal wellbore with perforated completion utilizing the designed computer class given in the paper.