• 한국전산유체공학회:학술대회논문집
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• 2000.10a
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• pp.15-24
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• 2000

The transient response of an airfoil to a rapidly deploying spoiler is numerically investigated using the turbulent compressible Navier-Stokes equations in two dimensions. Algebraic Baldwin-Lomax model, Wilcox $\kappa-\omega$ model, and SST $\kappa-\omega$ turbulence model are used to calculate the unsteady separated flow due to the rapid spoiler deployment. The spoiler motion relative to a stationary airfoil is treated by an overset grid hounded by a Dynamic Domain-Dividing Line which has been devised by the authors. The adverse effects of the spoiler influenced by the spoiler location and the hinge gap are expounded. The numerical results are in reasonably good agreement with the existing experimental data.

• Kyungpook Mathematical Journal
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• v.61 no.4
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• pp.831-843
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• 2021

In this paper we look at the three dimensional stagnation point flow problem over a rough rotating disk. We study the theoretical behaviour of the stagnation point flow, or forced flow, in the presence of a slip factor in which convective instability stationary modes appear. We make a numerical investigation of the effects of slip on the behaviour of the flow components of the stagnation point flow where the disk is rough. We provide, for the first time in the literature, a complete convective instability analysis and an energy analysis. Suitable similarity transformations are used to reduce the Navier-Stokes equations and the continuity equation into a system of highly non-linear coupled ordinary differential equations, and these are solved numerically subject to suitable boundary conditions using the bvp4c function of MATLAB. The convective instability analysis and the energy analysis are performed using the Chebyshev spectral method in order to obtain the neutral curves and the energy bars. We observe that the roughness of the disk has a destabilising effect on both Type-I and Type-II instability modes. The results obtained will be prominently treated as benchmarks for our future studies on stagnation flow.

• Journal of Ocean Engineering and Technology
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• v.19 no.3
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• pp.1-10
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• 2005

The effect of rotation on the unsteady laminar flaw past a circular cylinder is numerically investigated in the present study. The numerical solutions for the 2D Navier-Stokes equation obtained, using two different numerical methods. One is an accurate spectral method and the other is a finite volume method(FVM). First, the flaw around a stationary circular cylinder is investigated to understand the basic phenomenon of flaw separation and bluff body wake. Next, the flow characteristics of the laminar flow, past a rotating circular cylinder, are investigated, using a FVM developed in this study. By the effect of rotation, it is seen that values of lift increase, while the values of mean drag decrease. Further, the criteria of angular velocity, at which the Karman vorteces disappear, is also determined.

• Journal of computational fluids engineering
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• v.20 no.2
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• pp.103-108
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• 2015

Fluid-body interaction analysis of floating body with six degree-of-freedom motion is presented. In this study, three-dimensional incompressible Navier-Stokes equations are employed as a governing equation. The numerical method is based on a finite-volume approach on a cartesian grid together with a fractional-step method. To represent the body motion, the immersed boundary method for direct forcing is employed. In order to simulate the coupled six degree-of-freedom motion, Euler's equations based on rigid body dynamics are utilized. To represent the complex body shape, level-set based algorithm is utilized. In order to describe the free surface motion, the volume of fluid method utilizing the tangent of hyperbola for interface capturing scheme is employed. This study showed three different continuums(air, water and body) are simultaneously simulated by newly developed code. To demonstrate the applicability of the current approach, two different problems(dam-breaking with stationary obstacle and water entry) are simulated and all results are validated.