Pankaj Saha^a, Gautam Biswas^a,b,*

Frontiers in Heat and Mass Transfer, Vol.2, No.3, pp. 1-5, 2011, DOI:10.5098/hmt.v2.3.3008

Abstract Detailed flow structure in turbulent flows through a rectangular channel containing built-in winglet type vortex generators have been analyzed by means of solutions of the full Navier-Stokes equations using a Large-Eddy Simulation (LES) technique. The Reynolds number of investigation is 6000. The geometry of interest consists of a rectangular channel with a built-in winglet pair on the bottom wall with common-flow-down arrangement. The winglet pair induces streamwise longitudinal vortices behind it. The vortices swirl the flow around the axis parallel to the mainstream direction and disrupt the growth of thermal boundary layer entailing enhancement of… More >

Gregory Baker¹, Huaijian Zhang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.80, No.3&4, pp. 219-232, 2011, DOI:10.3970/cmes.2011.080.219

Abstract Boundary integral methods have proved very useful in the simulation of free surface motion, in part, because only information at the surface is necessary to track its motion. However, the velocity of the surface must be calculated quite accurately, and the error must be reasonably smooth, otherwise the surface buckles as numerical inaccuracies grow, leading to a failure in the simulation. For two-dimensional motion, the surface is just a curve and the boundary integrals are simple poles that may be removed, allowing spectrally accurate numerical integration. For three-dimensional motion, the singularity in the integrand, although More >

Hui-Fen Guo^1,2, Bin-Gang Xu^1,3, Sheng-Yan Li¹, Chong-Wen Yu²

CMES-Computer Modeling in Engineering & Sciences, Vol.80, No.2, pp. 87-112, 2011, DOI:10.3970/cmes.2011.080.087

Abstract Three-dimensional transient simulation is presented for swirling recirculating flow in a nozzle with a slotted-tube (different grooves) and the effect of the groove number is also investigated. The numerical results on the streamline angles are validated by experimental visualization using the surface oil flow technology. In the downstream center of the injectors, the vortex breakdown experiences a transition from bubble- to spiral- breakdown as time is increased. For all cases under study, as the sizes of two recirculation zones near the injector upstream wall and the step retain almost constant, the spiral breakdown shows a More >

J.L. Sereno¹, J.C.F. Pereira¹

CMES-Computer Modeling in Engineering & Sciences, Vol.73, No.1, pp. 23-44, 2011, DOI:10.3970/cmes.2011.073.023

Abstract The evolution of a two-dimensional vortex pair in ground effect was studied under the influence of random initial inputs comprising vortex strength (circulation) or initial vortex position. The paper addresses the questions of how do variations and uncertainties of initial conditions translate to the variability of vortex pair evolution. The stochastic solutions were obtained recurring to the Polynomial Chaos Expansion method of random processes applied to the Navier-Stokes equations for a laminar flow. The method quantifies the extent, dependence and propagation of uncertainty through the model system and, in particular, a methodology for the calculation More >

D.M.S. Albuquerque¹, J.M.C. Pereira¹, J.C.F. Pereira^1,2

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 >

Ruben Avila¹, Zhidong Han², Satya N. Atluri³

CMES-Computer Modeling in Engineering & Sciences, Vol.71, No.4, pp. 363-396, 2011, DOI:10.3970/cmes.2011.071.363

Abstract The two dimensional steady state Stokes equations are solved by using a novel MLPG-Mixed Finite Volume method, that is based on the independent meshless interpolations of the deviatoric velocity strain tensor, the volumetric velocity strain tensor, the velocity vector and the pressure. The pressure field directly obtained from this method does not suffer from the malady of checker-board patterns. Numerical simulations of the flow field, and trajectories of passive fluid elements in a new complex Stokes flow are also presented. The new flow geometry consists of three coaxial cylinders two of smaller diameter, that steadily More >

T. Uchiyama¹

FDMP-Fluid Dynamics & Materials Processing, Vol.7, No.4, pp. 371-388, 2011, DOI:10.3970/fdmp.2011.007.371

Abstract This study proposes a three-dimensional grid-free method to simulate particle-laden gas flows. It is based on a vortex method. The flow region is not resolved into computational grids, but the gas vorticity field is discretized by vortex elements. The behavior of the vortex element and the particle motion are simultaneously calculated by using the Lagrangian approach. Eight cubic cells are locally allocated around each particle to compute the effect of the particle motion on the gas flow. In each cell, the change in the vorticity due to the particle is calculated, and it is considered… More >

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 >

Hyun Ki¹, Jongwook Choi², Sungcho Kim²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.13, No.4, pp. 69-70, 2009, DOI:10.3970/icces.2009.013.069

Abstract The wake behind rotor blade is investigated by numerical and experimental approaches. Flow structure measured through PIV is compared with numerical analysis using commercial program of ANSYS CFX adopting the RNG k-ε turbulence model. Blade model fabricated by Rapid-Prototype method has the cross section of NACA0012 airfoil and the pitch angle of 10°. The rectangular blade of which rotating diameter (D) and chord length are 0.12 m and 0.024 m respectively rotates at 240 rpm. Horizontal and vertical directions of the blade are selected as x and z coordinates, respectively, the origin locates at the rotating… More >

Tae Soo Kim¹, Pa Ul Mun¹, Myung Kuk Lee¹, Jae Soo Kim^1,2

The International Conference on Computational & Experimental Engineering and Sciences, Vol.10, No.2, pp. 65-70, 2009, DOI:10.3970/icces.2009.010.065

Abstract This article has no abstract. More >