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  • Design, Optimization and CFD Simulation of a Nozzle for Industrial Cleaning Processes based on High-Pressure Water Jets
  • Abstract Three different kinds of nozzles, normally used in industrial processes for the cleaning of material surface by means of water jets at high pressure (a Cylindrical Contracting, a Taper Contracting and Stepped nozzle), are numerically simulated with the express intent to optimize the related efficiency (cleaning effectiveness). Although some of them are found to display interesting properties, simulation results indicate that a helix nozzle displays the best jetting performances. It is shown that, as compared to improvements obtained by simply changing the jetting angle, revolving the fluid released from the helix nozzle can be used to create a grinding wheel…
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  • Parametric Study of Bubble Kinematic Behaviour in a Centrifugal Vacuum Separator
  • Abstract The dynamics of dispersed bubbles in a centrifugal separator are investigated with the aim to improve the efficiency of the system. The prototype separator consists of a rotor, a base, a diverting disc, a shaft, an oil trapping impeller, a central pipe, an inlet section for contaminated oil, an outlet section for purified oil and an air outlet. A hydrodynamic model is developed to predict the complex influence of parameters such as the centrifugal force and vacuum pressure. In particular, three different force models are selected to analyze the effect of the added mass and Basset forces (also including inertia,…
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  • On the Vortex Formation Effect During the Application of a Nitrogen-Gas Assisted Laser-Fusion Cutting Technique to Stainless Steel
  • Abstract This paper focuses on the vortex formation effect during the application of a laser-fusion cutting technique. This industrial technique is typically associated with the ejection of a film of molten stainless steel blown off by a subsonic laminar jet of nitrogen gas used to assist the process. Without taking into account the transverse movement of the workpiece, we consider a 4 mm thick stainless steel plate. The resulting molten metal flow is assumed to be laminar, steady, viscous and incompressible. The numerical results reveal vortex structures adjacent to the walls at the entrance of the kerf, and a pair of…
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  • Lattice Boltzmann Simulation of MHD Double Dispersion Natural Convection in a C-shaped Enclosure in the Presence of a Nanofluid
  • Abstract MHD double-diffusive natural convective flow in a C-shaped enclosure filled with a Cu/Water nanofluid is investigated numerically using the Lattice Boltzmann Method (LBM). Much care is devoted to the validation of the numerical code. The effects exerted on the flow, concentration and temperature fields by different parameters such as the Rayleigh number (103−106), the nanoparticle volume concentration (0−0,1), the Lewis number (1-5), the Hartmann number (0−30) and different types of nanoparticles (Cu, Ag, Al2O3 and TiO3 are assessed in detail. Results for stream function, Nusselt and Sherwood numbers are presented and discussed for various parametric conditions. Results indicate that the…
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  • Numerical Investigations of an Integrated Phase-Change-Material Solar Collector
  • Abstract The objective of this study is to optimize the thermal performance of a solar collector. The solar collector is coupled to a building slab with a PCM layer. A mathematical model for the thermal behavior of the studied system is developed using the enthalpy method. The model parameters are defined and the resulting equations are solved iteratively. Several simulations were carried out to optimize the proposed heating system. The results show that the inlet temperature fluctuations are less pronounced than those at the outlet.
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  • Characteristics of a Hydromagnetic Non-Newtonian Squeeze Film Between Wide Parallel Rectangular Plates
  • Abstract The characteristics of a hydromagnetic non-Newtonian squeeze film formed between parallel rectangular plates under the application on an external magnetic field are investigated. A specific hydromagnetic non-Newtonian Reynolds equation is derived via pplication of the hydromagnetic flow theory together with the micro-continuum theory. It is found that the coupled effects of electrically conducting fluids and micropolar fluids result in a higher load capacity and a longer approaching time with respect to the non-conducting Newtonian case. These improved characteristics become more pronounced as the magnetic Hartmann parameter, the coupling parameter, and the fluid-gap parameter are increased.
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  • Acoustic Potential Generation under Acoustic Standing Waves Modeling using CFD Software
  • Abstract In the past few years, modeling of the Acoustic StandingWaves (ASW) phenomena has become a topic of great interest due to its theoretical connections with particle/cells manipulation techniques, which represent important tools in the biotechnology field. The present paper proposes a model based on the use of moving wall boundary conditions coupled with a viscous compressible fluid in a square channel. This model successfully achieved the generation of ASWs in the square cross-section for several resonance frequencies; the corresponding acoustic potential for the fundamental resonant mode and several harmonics have also been calculated and are discussed here.
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  • Theoretical Study of Solvation Effect on Diffusion Coefficient of Li Ion in Propylene Carbonate
  • Abstract Propylene carbonate (PC) and ethylene carbonate are known as good candidates of organic solvents to be used in Li-ion rechargeable batteries, since Li+ ions exhibit preferable charge-discharge characteristics with such solvents. On the other hand, polar solvents usually form solvation shells with solute ions, and cause a drastic reduction of ionic conductivity. Along these lines, there has been a curious question why the diffusion coefficient DLi of Li+ strongly depends on the salt concentration. In the present study, a theoretical model is developed on the basis of the Langevin equation in which the interactions between ions and solvent molecules are…
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  • Unsteady MHD Free Convection Past an Impulsively Started Isothermal Vertical Plate with Radiation and Viscous Dissipation
  • Abstract The fluctuating flow produced by magneto - hydrodynamic free convection past an impulsively started isothermal vertical plate is studied taking into account the effects of radiation and viscous dissipation. By using the similarity transformation, the governing equations are transformed into dimensionless form and then the system of nonlinear partial differential equations is solved by a perturbation technique. The considered uniform magnetic field acts perpendicular to the plate, which absorbs the fluid with a given suction velocity. A comparison is made in velocity and temperature profiles for two particular cases of real and imaginary time dependent functions. The effects of various…
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  • Heat Transfer Related to a Self-Sustained Oscillating Plane Jet Flowing Inside a Rectangular Cavity
  • Abstract Computations related to a heat transfer and fluid flow of a plane isothermal fully developed turbulent plane jet flowing into a rectangular hot cavity are reported in this paper. Both velocity and temperature distributions are computed by solving the two-dimensional Unsteady Reynolds Averaged Navier--Stokes (URANS) equations. This approach relies on one point statistical modeling based on the energy - specific dissipation (k-ω) turbulence model. The numerical simulations are carried out in the framework of a finite volume method. This problem is relevant to a wide range of practical applications including forced convection and the ventilation of mines, enclosure or corridors.…
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