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  • Open Access


    Analysis of Turbulent Flow on Tidal Stream Turbine by RANS and BEM

    Younes Noorollahi1,2,*, Mohammad-Javad Ziabakhsh Ganji1, Mohammadmahdi Rezaei1,2, Mojtaba Tahani3

    CMES-Computer Modeling in Engineering & Sciences, Vol.127, No.2, pp. 515-532, 2021, DOI:10.32604/cmes.2021.012386


    Nowadays, concerns arise because of the depletion of fossil fuel resources that forced scientists to develop new energy extraction methods. One of these renewable resources is tidal energy, where Iran has this potential significantly. There are many ways to obtain the kinetic energy of the fluid flow caused by the moon’s gravitational effect on seas. Using horizontal axis tidal turbines is one of the ways to achieve the kinetic energy of the fluid. Since this type of turbine has similar technology to horizontal axis wind turbines, they may be an appropriate choice for constructing a tidal

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  • Open Access


    Estimation of Turbulent Flow from Wall Information via Machine Learning

    Yousuke Shimoda1, Takahiro Matsumori1, Kazuki Sato1, Tatsuro Hirano1, Naoya Fukushima1,*

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.23, No.1, pp. 16-16, 2021, DOI:10.32604/icces.2021.08337

    Abstract Along with rapid development of computer technologies, a wide range of turbulent flows have been investigated by direct numerical simulations and the big databases have been built throughout the world. From the DNS results, we can investigate turbulent characteristics in three-dimensional space and time. In the laboratory experiment, we can apply sophisticated laser diagnostics technique to measure flow field non-invasively in research. On actual equipment, it is very difficult to get the flow field data away from the wall. We can measure only wall information, such as wall shear stresses and pressure. When we predict… More >

  • Open Access


    LES Investigation of Drag-Reducing Mechanism of Turbulent Channel Flow with Surfactant Additives

    Jingfa Li1, Bo Yu1,*, Qianqian Shao2, Dongliang Sun1

    CMES-Computer Modeling in Engineering & Sciences, Vol.125, No.2, pp. 541-563, 2020, DOI:10.32604/cmes.2020.011835

    Abstract In this work, the drag-reducing mechanism of high-Reynoldsnumber turbulent channel flow with surfactant additives is investigated by using large eddy simulation (LES) method. An N-parallel finitely extensible nonlinear elastic model with Peterlin’s approximation (FENE-P) is used to describe the rheological behaviors of non-Newtonian fluid with surfactant. To close the filtered LES equations, a hybrid subgrid scale (SGS) model coupling the spatial filter and temporal filter is applied to compute the subgrid stress and other subfilter terms. The finite difference method and projection algorithm are adopted to solve the LES governing equations. To validate the correctness More >

  • Open Access


    Computational Simulation of Turbulent Flow Around Tractor-Trailers

    D. O. Redchyts1, E. A. Shkvar2, *, S. V. Moiseienko3

    FDMP-Fluid Dynamics & Materials Processing, Vol.16, No.1, pp. 91-103, 2020, DOI:10.32604/fdmp.2020.07933

    Abstract A method to evaluate the properties of turbulent flow in proximity to the vehicle and close to the ground surface has been elaborated. Numerical simulations have been performed on the basis of the Unsteady Reynolds-averaged Navier-Stokes equations (URANS) written with respect to an arbitrary curvilinear coordinate system. These equations have been solved using the Spalart-Allmaras differential one-parametric turbulence model. The method of artificial compressibility has been used to improve the coupling of pressure and velocity in the framework of a finite volume approach. Time-averaged distributions of pressure fields, velocity components, streamlines in the entire area… More >

  • Open Access


    Control of Karman Vortex Street By Using Plasma Actuators

    D. O. Redchyts1, E. A. Shkvar2,*, S. V. Moiseienko3

    FDMP-Fluid Dynamics & Materials Processing, Vol.15, No.5, pp. 509-525, 2019, DOI:10.32604/fdmp.2019.08266

    Abstract A mathematical model for unsteady electro- and aerodynamic processes in the presence of a plasma actuator has been elaborated through physical modeling of the dielectric barrier discharge. A specialized computational fluid dynamics package has been developed accordingly in order to calculate steady and unsteady laminar and turbulent flows. For the numerical simulation of the dielectric barrier discharge, in particular, two equations have been added to the Navier-Stokes equations and solved. They describe the distribution of the applied voltage and the charged particles density. The impact of the plasma actuator on air has been accounted for… More >

  • Open Access


    Experimental and Numerical Studies on Heat Transfer and Fluid Flow in a Duct Fitted with Inclined Baffles

    W. A. El-Askary, A. Abdel-Fattah

    CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.4, pp. 425-458, 2012, DOI:10.3970/cmes.2012.083.425

    Abstract In the present paper, experimental and numerical studies of heat transfer and the frictional head loss of turbulent flow in a duct with a heated upper surface are performed. Four different arrangements are considered (case 1: without baffles, case 2: one perforated baffle on the upper wall and one solid baffle on the lower wall, case 3: one perforated baffle on the upper wall and one perforated baffle on the lower wall and case 4: two perforated baffles on the upper wall). A numerical code developed by the present authors is simultaneously presented including four… More >

  • Open Access


    Computations of a Compressible Turbulent Flow in a Rocket Motor-Chamber Configuration with Symmetric and Asymmetric Injection

    W.A. El-Askary1,2, A. Balabel2, S.M. El-Behery2, A. Hegab3

    CMES-Computer Modeling in Engineering & Sciences, Vol.82, No.1, pp. 29-54, 2011, DOI:10.32604/cmes.2011.082.029

    Abstract In the present paper, the characteristics of compressible turbulent flow in a porous channels subjected to either symmetric or asymmetric mass injection are numerically predicted. A numerical computer-program including different turbulence models has been developed by the present authors to investigate the considered flow. The numerical method is based on the control volume approach to solve the governing Reynolds-Averaged Navier-Stokes (RANS) equations. Turbulence modeling plays a significant role here, in light of the complex flow generated, so several popular engineering turbulence models with good track records are evaluated, including five different turbulence models. Numerical results… More >

  • Open Access


    Adaptively Refined Hybrid FDM-RBF Meshless Scheme with Applications to Laminar and Turbulent Viscous Fluid Flows

    S. Gerace1, K. Erhart1, E. Divo1,2, A. Kassab1

    CMES-Computer Modeling in Engineering & Sciences, Vol.81, No.1, pp. 35-68, 2011, DOI:10.3970/cmes.2011.081.035

    Abstract The focus of this work is to demonstrate a novel approach to true CFD automation based on an adaptive Cartesian point distribution process coupled with a Meshless flow solution algorithm. As Meshless method solutions require only an underlying nodal distribution, this approach works well even for complex flow geometries with non-aligned domain boundaries. Through the addition of a so-called shadow layer of body-fitted nodes, application of boundary conditions is simplified considerably, eliminating the stair-casing issues of typical Cartesian-based techniques. This paper describes the approach taken to automatically generate the Meshless nodal distribution, along with the More >

  • Open Access


    Computation of the Turbulent Flow in a Square Duct Using a Cubic Low-Reynolds Stress Model

    H. Naj1,2,3, G. Mompean1,2

    CMES-Computer Modeling in Engineering & Sciences, Vol.53, No.2, pp. 181-206, 2009, DOI:10.3970/cmes.2009.053.181

    Abstract The aim of this work is to predict numerically the turbulent flow through a straight square duct using a nonlinear stress-strain model. The paper considers the application of the Craft et al.'s model [Craft, Launder, and Suga (1996)] to the case of turbulent incompressible flow in a straight square duct. In order to handle wall proximity effects, damping functions are introduced. Using a priori and a posteriori investigations, we show the performance of this model to predict such flows. The analysis of the flow anisotropy is made using the anisotropy-invariant map proposed by Lumley and More >

  • Open Access


    Solution of Incompressible Turbulent Flow by a Mesh-Free Method

    R. Vertnik1, B. Šarler2

    CMES-Computer Modeling in Engineering & Sciences, Vol.44, No.1, pp. 65-96, 2009, DOI:10.3970/cmes.2009.044.065

    Abstract The application of the mesh-free Local Radial Basis Function Collocation Method (LRBFCM) in solution of incompressible turbulent flow is explored in this paper. The turbulent flow equations are described by the low - Re number k-emodel with Jones and Launder [Jones and Launder (1971)] closure coefficients. The involved velocity, pressure, turbulent kinetic energy and dissipation fields are represented on overlapping 5-noded sub-domains through collocation by using multiquadrics Radial Basis Functions (RBF). The involved first and second derivatives of the fields are calculated from the respective derivatives of the RBF's. The velocity, turbulent kinetic energy and… More >

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