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  • Open Access


    Probabilistic Collocation used in a Two-Step approach for \\efficient uncertainty quantification in computational fluid dynamics.

    G.J.A. Loeven1,2, H. Bijl3

    CMES-Computer Modeling in Engineering & Sciences, Vol.36, No.3, pp. 193-212, 2008, DOI:10.3970/cmes.2008.036.193

    Abstract In this paper a Two-Step approach is presented for uncertainty quantification for expensive problems with multiple uncertain parameters. Both steps are performed using the Probabilistic Collocation method. The first step consists of a sensitivity analysis to identify the most important parameters of the problem. The sensitivity derivatives are obtained using a first or second order Probabilistic Collocation approximation. For the most important parameters the probability distribution functions are propagated using the Probabilistic Collocation method using higher order approximations. The Two-Step approach is demonstrated for flow around a NACA0012 airfoil with eight uncertain parameters in the More >

  • Open Access


    Calculation of a Deformable Membrane Airfoil in Hovering Flight

    D.M.S. Albuquerque1, J.M.C. Pereira1, J.C.F. Pereira1,2

    CMES-Computer Modeling in Engineering & Sciences, Vol.72, No.4, pp. 337-366, 2011, DOI:10.3970/cmes.2011.072.337

    Abstract A numerical study of fluid-structure interaction is presented for the analysis of viscous flow over a resonant membrane airfoil in hovering flight. A flexible membrane moving with a prescribed stroke period was naturally excited to enter into 1st, 2nd and 3rd mode of vibration according to the selected membrane tension. The Navier-Stokes equations were discretized on a moving body unstructured grid using the finite volume method. The instantaneous membrane position was predicted by the 1D unsteady membrane equation with input from the acting fluid flow forces. Following initial validation against reported rigid airfoils predictions, the… More >

  • Open Access


    Accurate True Direction Solutions to the Euler Equations Using a Uniform Distribution Equilibrium Method

    Alex Ferguson1, Matthew R. Smith2, J.-S. Wu3

    CMES-Computer Modeling in Engineering & Sciences, Vol.63, No.1, pp. 79-100, 2010, DOI:10.3970/cmes.2010.063.079

    Abstract A novel approach for the use of multiple continuous uniform distributions for reconstruction of the Maxwell-Boltzmann equilibrium probability distribution function is used for the solution of one and two dimensional Euler equations. The Uniform distribution Equilibrium Flux Method (UEFM) is a kinetic-theory based flux solver which calculates true directional, volume to volume fluxes based on integration (over velocity space and physical space) of a sum of uniform probability distribution functions working to approximate the equilibrium distribution function. The resulting flux expressions contain only the Heaviside unit step function and do not require the evaluation of More >

  • Open Access


    Efficient Engineering Prediction of Turbulent Wing Tip Vortex Flows

    Sung-Eun Kim1, Shin Hyung Rhee2

    CMES-Computer Modeling in Engineering & Sciences, Vol.62, No.3, pp. 291-310, 2010, DOI:10.3970/cmes.2010.062.291

    Abstract Turbulent flow past a finite wing has been computed to assess the fidelity of modern computational fluid dynamics in predicting tip vortex flows. The efficacy of a feature-adaptive local mesh refinement to resolve the steep gradients in the flow field near the tip vortex is demonstrated. The impact of turbulence modeling is evaluated using several popular eddy viscosity models and a Reynolds stress transport model. The results indicate that the combination of a computational mesh with an adequate resolution, high-order spatial discretization scheme along with the use of advanced turbulence models can predict tip vortex More >

  • Open Access


    Numerical Simulations of Flows over a Pair of Cylinders at Different Arrangements using the Immersed Boundary Method

    A.R. da Silva1, A. Silveira-Neto2,3, D.A. Rade2,4, R.Francis4, E.A. Santos4

    CMES-Computer Modeling in Engineering & Sciences, Vol.50, No.3, pp. 285-304, 2009, DOI:10.3970/cmes.2009.050.285

    Abstract In the context of computational fluid dynamics a numerical investigation of incompressible flow around fixed pairs of rigid circular cylinders was carried out. The two-dimensional filtered Navier-Stokes equations with the Smagorinsky sub-grid scale model were solved using a Cartesian non-uniform grid. The immersed Boundary Method with the Virtual Physical Model was used in order to model the presence of two circular cylinders embedded in the flow. The fractional time step method was used to couple pressure and velocity fields. The simulations were carried out for Reynolds number equal to 72,000 for pitch ratio equal to More >

  • Open Access


    A Computational Fluid Dynamics Study of a 2D Airfoil in Hovering Flight Under Ground Effect

    J.M.C.Pereira1, N.A.R.Maia1, J.C.F.Pereira1

    CMES-Computer Modeling in Engineering & Sciences, Vol.49, No.2, pp. 113-142, 2009, DOI:10.3970/cmes.2009.049.113

    Abstract We present a 2D incompressible Navier-Stokes numerical simulation of a virtual model of an elliptic, or flat plate, foil in hovering flight configuration. Computations obtained with a general purpose solver were validated against reference data on forward flapping flight, normal or dragonfly hovering. The moving mesh technique allows airfoil translation and angular mesh movement accompaining the airfoil stroke motion. Close to the ground the mesh deforms to occupy the narrow computational domain formed between the airfoil and the ground. Computations have been carried out for some parameters, including the distances h between the foil center and… More >

  • Open Access


    Fluid dynamic analysis of different Yacht configurations with VOF method

    R. Savino1, M . Visone2, D. Rossetto3, V. D'Oriano4

    FDMP-Fluid Dynamics & Materials Processing, Vol.11, No.4, pp. 331-341, 2015, DOI:10.3970/fdmp.2015.011.331

    Abstract This paper presents two applications of Computational Fluid Dynamics (CFD) to super and mega yacht design, based on the Volume of Fluid method. After an overview of recent literature on the subject, the analysis of the hydrodynamic performances of different hull configurations and of different appendage configurations is presented. More >

  • Open Access


    Acoustic Potential Generation under Acoustic Standing Waves Modeling using CFD Software

    C. S. Iorio1, C. Perfetti1

    FDMP-Fluid Dynamics & Materials Processing, Vol.11, No.1, pp. 27-48, 2015, DOI:10.3970/fdmp.2015.011.027

    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 More >

  • Open Access


    Computational Fluid Dynamics Modeling of the Effect Of Rotation During Reaming into the Intramedullary Canal of a Long Bone

    J. Bahen1, O. Gaber1, K. Behdinan2, J. De Beer3, P. Zalzal4, M. Papini1, M. Z. Saghir1

    FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.4, pp. 343-352, 2005, DOI:10.3970/fdmp.2005.001.343

    Abstract The penetration of the reamer into the medullary cavity can be compared to a piston entering a cylinder filled with viscous fluid. When the flutes of the reamer are clogged with bone debris, fat and marrow, the piston effect is magnified and larger pressures are usually obtained. This paper considers a reamer with clogged flutes and investigates whether the rotation speed of the reamer has a significant influence on the pressure within the intramedullary cavity. The effect of reamer rotation speed on the pressure distribution within the bone is investigated numerically by solving the full More >

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