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  • Open Access

    ABSTRACT

    Effect of the Reynolds Number on the Flow Pattern in a Stenotic Right Coronary Artery

    Biyue Liu1

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.1, No.1, pp. 35-40, 2007, DOI:10.3970/icces.2007.001.035

    Abstract It is well known that the Reynolds number has a significant effect on the blood flow in human arteries. We developed a three dimensional model with simplified geometry for a diseased right coronary artery segment to study the influence of the Reynolds number on the flow pattern in a stenotic coronary artery. Computations were carried out under physiological flow conditions to examine how the characteristics of the flow, such as the flow velocity and the pressure drop along the inner wall, change corresponding to the varying of the blood viscosity or to the varying of the mean inlet flow rate.… More >

  • Open Access

    ARTICLE

    2D Incompressible Viscous Flows at Moderate and High Reynolds Numbers

    Alfredo Nicolás1, Blanca Bermúdez2

    CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.5, pp. 441-452, 2004, DOI:10.3970/cmes.2004.006.441

    Abstract 2D incompressible vicous flows from the unsteady Navier-Stokes equations in stream function-vorticity variables are presented. The results are obtained using a simple numerical procedure based on a fixed point iterative process to solve the nonlinear elliptic system that results once a second order time discretization is performed. Flows on the unregularized unit driven cavity are reported up to Reynolds numbers Re=5000 to compare them with those reported by other authors and supposed to be correct. Various long time computations are presented for Re=10000 to see its evolution as time-dependent flow. Moreover, results are reported for Re=10000, Re=15000 and Re=20000 to… More >

  • Open Access

    ARTICLE

    The Effect of the Reynolds Number on Lateral Migration of Nonneutrally-Buoyant Spherical Particles in Poiseuille Flow

    S.-C. Hsiao1, M.S. Ingber2

    CMC-Computers, Materials & Continua, Vol.1, No.1, pp. 51-58, 2004, DOI:10.3970/cmc.2004.001.051

    Abstract The lateral migration of nonneutrally-buoyant spherical particles in Poiseuille flow is investigated numerically using the boundary element method. In particular, the steady, Navier-Stokes equations are solved using a classical domain integration method treating the nonlinear terms as pseudo-body forces. The numerical results for the lateral migration velocity are compared with experimental data. The numerical results indicate that the lateral migration velocity does not scale linearly with the Reynolds number. The methodology is extended to include non-Newtonian power-law fluids. The migration velocity is significantly affected for particles suspended in this class of fluids and can actually change direction for large values… More >

  • Open Access

    ARTICLE

    Aerodynamic Performance of DragonflyWing with Well-designed Corrugated Section in Gliding Flight

    Zilong Zhang1, Yajun Yin2, Zheng Zhong1,3, Hongxiao Zhao1

    CMES-Computer Modeling in Engineering & Sciences, Vol.109-110, No.3, pp. 285-302, 2015, DOI:10.3970/cmes.2015.109.285

    Abstract Dragonflies possess the highly corrugated wings which distinguish from the ordinary airfoils. To unlock the secrets of the dramatic flight ability of dragonflies, it will be of great significance to investigate the aerodynamic contribution of the corrugations. In this paper, a group of corrugated airfoils were specially designed based on the geometrical characteristics of a typical dragonfly wing. The two-dimensional Navier-Stokes equations were solved using the finite volume method, and the coefficients of lift and drag of the studied airfoils were calculated and compared with those of a flat airfoil and a NACA0008 airfoil. The obtained numerical results illustrated that… More >

  • Open Access

    ARTICLE

    Large Eddy Simulation of Three Dimensional Impinging Jets

    Nadjib Ghiti1

    CMES-Computer Modeling in Engineering & Sciences, Vol.99, No.3, pp. 195-208, 2014, DOI:10.3970/cmes.2014.099.195

    Abstract This paper presents a large eddy simulation of three dimensional vertically impinging jet on a horizontal plate. The air impinging jet was simulated using the perturbed method based on a high vortex number in the jet inlet for different ranges of Reynolds number Re= 6000, 8000, 10000, 12000, 14000 and for the same distance between the jet and the impinging plate. The effect of the Reynolds number of the air jet impinging on a horizontal plate was studied; the study showed that the vorticity magnitude is increased with the increasing of the Reynolds number. The turbulent flow jet was decomposed… More >

  • Open Access

    ARTICLE

    CFD and Experimental Investigations of Drag Force on Spherical Leak Detector in Pipe Flows at High Reynolds Number

    ShiXu Guo1, Shili Chen1, Xinjing Huang1, Yu Zhang1, Shijiu Jin1

    CMES-Computer Modeling in Engineering & Sciences, Vol.101, No.1, pp. 59-80, 2014, DOI:10.3970/cmes.2014.101.059

    Abstract Spherical leak detectors can detect very tiny leakage in pipelines and have low risk of blockage. In this paper the passing ability of the detector in the vertical segment of a pipe was studied using CFD simulations and experiments. The Reynolds number for the sphere exceeds 104 at the economical velocity range for oil pipelines, and there were few researches related to the hydrodynamic force on the sphere by the pipe flow at high Reynolds number. For sphere with different sizes and density, and at different flow rates, more than 100 3-D steady numerical simulations were carried out. The simulation… More >

  • Open Access

    ARTICLE

    Multi-Point Shape Optimization of Airfoils at Low Reynolds Numbers

    D.N. Srinath1, Sanjay Mittal1, Veera Manek2

    CMES-Computer Modeling in Engineering & Sciences, Vol.51, No.2, pp. 169-190, 2009, DOI:10.3970/cmes.2009.051.169

    Abstract A continuous adjoint method is formulated and implemented for the multi-point shape optimization of airfoils at low Re. The airfoil shape is parametrized with a non-uniform rational B-Spline (NURBS). Optimization studies are carried out for two different objective functions. The first involves an inverse function on the lift coefficient over a range of Re. The objective is to determine a shape that results in a lift coefficient of 0.4 at three values of Re: 10, 100 and 500. The second objective involves a direct function on the lift coefficient over a range of angles of attack,a. The lift coefficient is… More >

  • Open Access

    ARTICLE

    Performance of Multiquadric Collocation Method in Solving Lid-driven Cavity Flow Problem with Low Reynolds Number

    S. Chantasiriwan1

    CMES-Computer Modeling in Engineering & Sciences, Vol.15, No.3, pp. 137-146, 2006, DOI:10.3970/cmes.2006.015.137

    Abstract The multiquadric collocation method is the collocation method based on radial basis function known as multiquadrics. It has been successfully used to solve several linear and nonlinear problems. Although fluid flow problems are among problems previously solved by this method, there is still an outstanding issue regarding the influence of the free parameter of multiquadrics (or the shape parameter) on the performance of the method. This paper provides additional results of using the multiquadric collocation method to solve the lid-driven cavity flow problem. The method is used to solve the problem in the stream function-vorticity formulation and the velocity-vorticity formulation.… More >

  • Open Access

    ARTICLE

    A Group Preserving Scheme for Burgers Equation with Very Large Reynolds Number

    Chein-Shan Liu1

    CMES-Computer Modeling in Engineering & Sciences, Vol.12, No.3, pp. 197-212, 2006, DOI:10.3970/cmes.2006.012.197

    Abstract In this paper we numerically solve the Burgers equation by semi-discretizing it at the n interior spatial grid points into a set of ordinary differential equations: u· = f(u,t), u ∈ Rn. Then, we take the dissipative behavior of Burgers equation into account by considering the magnitude ||u|| as another component; hence, an augmented quasilinear differential equations system X˙ = AX with X := (uT,||u||)T ∈ Mn+1 is derived. According to a Lie algebra property of A∈so(n,1) we thus develop a new numerical scheme with the transformation matrix G∈SOo(n,1) being an element of the proper orthochronous Lorentz group.… More >

  • Open Access

    ARTICLE

    Parametric Study of a Pitching Flat Plate at Low Reynolds Numbers

    Yongsheng Lian 1

    CMES-Computer Modeling in Engineering & Sciences, Vol.72, No.1, pp. 1-16, 2011, DOI:10.3970/cmes.2011.072.001

    Abstract In this paper we simulate the unsteady, incompressible, and laminar flow behavior over a flat plate with round leading and trailing edges. A pressure-Poisson method is used to solve the incompressible Navier-Stokes equations. Both convection and diffusion terms are discretized using a second-order accurate central difference method. A second-order accurate split-step scheme with an Adam's predictor corrector time-stepping method is adopted for the time integration. An overlapping moving grid approach is employed to dynamically update the grid due to the plate motion. The effects of the pitch rate, Reynolds number, location of pitch axis, and computational domain size are investigated.… More >

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