Current Issue : April - June Volume : 2017 Issue Number : 2 Articles : 6 Articles
This paper investigates the distributed shortest-distance problem of multiagent systems where agents satisfy the same continuous time\ndynamics. The objective of multiagent systems is to find a common point for all agents to minimize the sum of the distances\nfrom each agent to its corresponding convex region. A distributed consensus algorithm is proposed based on local information. A\nsufficient condition also is given to guarantee the consensus. The simulation example shows that the distributed shortest-distance\nconsensus algorithm is effective for our theoretical results....
A theoretical approach is developed for solving for the Reynolds stress in turbulent\nflows, and is validated for canonical flow geometries (flow over a flat plate, rectangular\nchannel flow, and free turbulent jet). The theory is based on the turbulence momentum\nequation cast in a coordinate frame moving with the mean flow. The formulation\nleads to an ordinary differential equation for the Reynolds stress, which can\neither be integrated to provide parameterization in terms of turbulence parameters\nor can be solved numerically for closure in simple geometries. Results thus far indicate\nthat the good agreement between the current theoretical and experimental/DNS\n(direct numerical simulation) data is not a fortuitous coincidence, and in the least it\nworks quite well in sensible ways in canonical flow geometries. A closed-form solution\nfor the Reynolds stress is found in terms of the root variables, such as the mean\nvelocity, velocity gradient, turbulence kinetic energy and a viscous term. The form of\nthe solution also provides radically new insight on how the Reynolds stress is generated\nand distributed....
While finite volume methodologies (FVM) have predominated in fluid flow computations,\nmany flow problems, including groundwater models, would benefit from the\nuse of boundary methods, such as the Complex Variable Boundary Element Method\n(CVBEM). However, to date, there has been no reporting of a comparison of computational\nresults between the FVM and the CVBEM in the assessment of flow field\ncharacteristics. In this work, the CVBEM is used to develop a flow field vector outcome\nof ideal fluid flow in a 90-degree bend which is then compared to the computational\nresults from a finite volume model of the same situation. The focus of the\nmodelling comparison in the current work is flow field trajectory vectors of the fluid\nflow, with respect to vector magnitude and direction. Such a comparison is necessary\nto validate the development of flow field vectors from the CVBEM and is of interest\nto many engineering flow problems, specifically groundwater modelling. Comparison\nof the CVBEM and FVM flow field trajectory vectors for the target problem of\nideal flow in a 90-degree bend shows good agreement between the considered methodologies....
The problem is considered on mixed convection flow due to the effect of small amplitude oscillations of a viscous\nincompressible fluid along a horizontal circular cylinder. Direct implicit finite-difference scheme is employed to\nsolve the dimensionless system of partial differential equations. In case of steady flow, the solutions are presented\nas functions of the curvature parameter X on the entire surface of the cylinder and there is a visual comparison with\nthe existing result. For fluctuating flow, considering Prandtl number, Pr=1.0, the results are shown graphically in\nterms of amplitude and phase of the Nusselt number for different values of buoyancy parameter Ã?». Due to the effect\nof Ã?» and frequency parameter Ãâ?°, streamlines and isotherms as well as transient shear stress and heat transfer are\nillustrated in the interplay of study....
In this article, a numerical investigation of vapor condensation in a two-dimensional ordered microchannel was conducted\nwith computational fluid dynamics software Fluent. A simplified physical model was built up to simulate a rectangular\nchannel filled with particles. A constant wall heat flux was added to the side walls of the rectangular channel.\nVolume of fluid model was adopted to pursue the interface of the gas and liquid. The results showed that a better heat\ntransfer performance could be obtained with the porous structure. The local heat transfer coefficient obtained from\nsimulation was in good accordance with the former experimental data, which increased with the increase in fluid velocity\nand decreased along the flow direction. Parametric analyses were conducted concerning the effects of initial vapor velocity\nu0, initial temperature T0, and wall heat flux qw on local heat transfer coefficient. The velocity u0 played a significant\nrole during the process of condensation. Temperature distributions along the porous channel and side walls were also\nanalyzed. The results showed that the temperature decreased along the flow direction and increased with the increase\nin fluid velocity....
An unsteady squeezing flow of Casson fluid having magnetohydrodynamic (MHD) effect and passing through porous medium\nchannel is modeled and investigated. Similarity transformations are used to convert the partial differential equations (PDEs) of non-\nNewtonian fluid to a highly nonlinear fourth-order ordinary differential equation (ODE). The obtained boundary value problem\nis solved analytically by Homotopy Perturbation Method (HPM) and numerically by explicit Runge-Kutta method of order 4. For\nvalidity purpose, we compare the analytical and numerical results which show excellent agreement. Furthermore, comprehensive\ngraphical analysis has been made to investigate the effects of various fluid parameters on the velocity profile. Analysis shows that\npositive and negative squeeze number ...
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