Papers by Keyword: Fluid Flow

Abstract: In this paper, a numerical study of fluid flow through perforated panels with square holes and open-cell material with cubic cells is presented. Structures with a wide variety of porosities (0.15<φ<0.94) and Reynolds numbers (0.01<Re<6000) are studied. Among the various outcomes obtained, the results indicate that pressure gradient vs Reynolds number exhibits three different forms of variation, including linear (Re<1), nonlinear (1≤Re<4000), and one where the pressure gradient is virtually constant with the Reynolds number (Re≥4000). The results were provided in terms of loss factor, but also of intrinsic permeability and the Forchheimer coefficient. Relationships that connect porosity to the loss factor, intrinsic permeability, and Forchheimer coefficient are also presented. These findings may prove useful in better understanding the flow behaviors in perforated panels and cell metal foams, which have a wide range of applications.

Abstract: A study of the heat transport and fluid flow behaviour around a tilted elliptical cylinder that is located concentrically in a square enclosure whose top horizontal wall is driven by a lid in the positive x-direction is presented. Due to the disparities in the results of convective heat transfer in square cavities in the literature, this study seeks to investigate the combined effects of the Grashof number, Aspect ratio of the geometry, and Elliptical cylinder inclination angle on the dynamics of thermal and flow fields within the geometry investigated. COMSOL Multiphysics 5.5 version was used to resolve the non-dimensional transport equations, while simulations were performed to examine the implications of salient parameters such as the elliptical inclination angle , Grashof number and aspect ratio . The simulation outcomes are displayed as average Nusselt numbers, velocity streamlines, and isothermal contours. Findings from this study show that an increase in aspect ratio resulted in increased heat transfer at the elliptical cylinder wall, with the highest rate of heat transfer occurring when .0. Furthermore, the inclination angle increments when Gr= and led to a reduction in the average Nusselt number of the elliptical cylinder wall. At and AR ranges of , the value of the elliptical cylinder wall increased as the ellipse's inclination angle increased. The findings of this study have found use in heat transfer systems, particularly electronic cooling and nuclear technologies.

Abstract: Energy harvesting has been at the forefront of research due to the significant interest in green energy sources, especially for powering remote sensors in structural health monitoring of coastal and offshore facilities. This work reports the magnet-actuated piezoelectric harvesters (M-APH) that use magnetic coupling to actuate piezoelectric film-embedded silicon rubber strips for energy harvesting from fluids. The piezo-silicon strips are deflected by the tip-magnets in the actuation system, such that the M-APH can effectively be triggered to generate electrical energy from vibration. The M-APH prototypes are printed using 3D printing technology, and the experiments are conducted to determine the output electrical voltage using a rectifier. Strip properties are varied to study the geometric influence (i.e., thickness and shape) on the energy performance. The electrical performance was evaluated for each curved piezoelectric strip and straight strips according to the piezoelectric material used. The reported M-APH can be applied to various fluids for energy harvesting.

Abstract: In this paper, we cope with the problem of presents a numerical analysis for heat transfer in a duct with geometry circular annular elliptical using the Galerkin-based integral method. The analysis is performed for different geometries of the duct (circular annular circular and circular annular elliptical), and the method is validated for circular cylindrical geometry. Parameters such as mean temperature and mean and location Nusselt numbers for two boundary conditions: constant wall temperature and axial constant heat flux in the wall with constant wall temperature are presented and analyzed.

Abstract: This work is based on a numerical study of the fluid-structure thermal coupling in a concrete slab intended for habitable heating. A rectangular cross-section pipe in which a hot fluid flow is installed in this concrete slab. The Navier-Stokes equations that govern this flow have been solved numerically. To this end, these equations have been discretized by an implicit finite difference method. The systems of algebraic equations thus obtained have been solved by the Gauss and Thomas algorithms. The conduction equation in the concrete slab was solved using the same methodology as that of flow. In fact, we have based on an algorithm that makes an unsteady solid medium interact with a fluid medium consisting of permanent states series while ensuring the equality of fluxes and temperatures on the common interface between both media at every moment. The numerical simulation of heat transfer and the thermal behavior of the heating slab were analyzed for different parameters influencing thermal diffusion. The results obtained by the numerical model adopted for the control of the fluid-structure coupling are in good agreement with those of the literature results.

Abstract: The present work is conducted for studying the natural convection in a circular enclosure that contains three equal-sized cylinders in tandem arrangement. The outer cylinder has a cold surface and the enclosure internals have hot surfaces. The relation between the density of the fluid and the temperature is treated by the Boussinesq approximation. The fluid used for the investigation is Newtonian and incompressible. The results present the roles of some non-dimensional parameters (Rayleigh (Ra) and Prandtl (Pr) numbers) on the buoyancy-driven flow and the convective heat transfer. The obtained results revealed an intensification of the v-velocity component in the annular space and an enhancement in the heat transfer rates with the rise of Rayleigh number.

Abstract: A steady, 2-D, viscous fluid flow past a fixed solid cylinder of radius ‘a’ has been considered where the density is constant for considered fluid. The flow of fluid happens in 3 regions namely fluid, porous and fluid region. The constitutive equations for the flow in porous and fluid regions are Brinkman and Stokes equations respectively. The variation of flow patterns by means of streamlines has been analysed by applying different boundary conditions at the interface of fluid – porous and porous – fluid regions and also on the surface of the solid cylinder assuming that the even velocity far off from the fluid region. The nature of streamlines is observed for the distinct values of porous parameter ‘σ’ and the corresponding flow behaviour is analysed graphically. From the obtained results it is noticed that increase in porous parameter, suppress the fluid flow in porous region consequently the fluid moves away from the solid cylinder.

Abstract: The development of materials with specific properties is a relevant engineering topic. The composite materials, hybrid of metal structures embedded in polymer matrices, are intensively used in mechanical systems in order to obtain materials with high resistance associated to low weight. To fabricate these materials, it is necessary to inject the polymeric resin in a liquid state in mold cavity, which characterizes a multiphase flow as the air present in the mold is repelled by strategically projected outlets. In this sense, a correct knowledge of the flow mechanisms existing in the molding process is necessary to guide the parts manufacture. Through the Ansys FLUENT^® software, this work performs a mathematical modeling of the resin transient flow inside a mold where metal wires are located and presents a numerical solution that describes, through calculations of volumetric fractions, velocity and pressure fields, and the fluid dynamic aspects that characterize the liquid molding process. It has been observed that the pressure required to maintain the constant flow at the mold inlet is increased until 80s of the process, when the steady state condition is achieved, that there is a greater resistance to mold filling in the side regions close to the mold wall due to the metal wires arrangement and that the air removal velocity that occurs due to resin injection becomes very low from the moment that resin reaches the mold outlets.

Abstract: This work provides information about polymer composite manufacturing by using liquid composite material molding, with particular reference to resin transfer molding process (RTM). Herein, several topics related to porous media, fluid flow, mathematical modeling, computational methods, composite manufacturing and industrial applications were presented. Simulation of resin flow into a fibrous (reinforcement) inserted in a parallelepiped mold has been performed, using the Ansys FLUENT^® software, and different results of resin volumetric fraction, stream lines and pressure distribution inside the mold, and volumetric fraction always flow rate (inlet and outlet gates) of the resin, as a function of filling time, have been presented and discussed.

Abstract: In this paper, the steady-state flow of non-Newtonian fluid in a planar channel with sudden expansion is investigated. The rheological behavior of this media is described by the Herschel-Bulkley model. To determine both steady-state velocity and pressure fields, a numerical algorithm based on the relaxation method and SIMPLE procedure is used.The mathematical problem statement includes three non-dimensional parameters: the Reynolds number, the Bingham number (non-dimensional viscoplasticity parameter), and the power-law index. The results of numerical simulation are obtained in a range of the Reynolds number 1 ≤ Re ≤ 40, Bingham number 0 ≤ Se ≤ 2, and power-law index 0.4 ≤ k ≤ 2 (for shear thinning, Newtonian, and shear thickening fluids).The distribution of the main fluid flow characteristics and localization of the two-dimensional region in an expansion zone is presented. The impact of main parameters of the problem on a dead zone distribution in the fluid flow is shown.