• 한국전산유체공학회:학술대회논문집
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• 2001.05a
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• pp.105-110
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• 2001

An Eulerian-Lagrangian method, so called immersed boundary method, is used for analysing viscous flow around arbitrary bodies, where governing equations are discretized on a regular grid by using a finite volume method. To improve the accuracy of flow near body boundaries, a second-order accurate interpolation scheme is used and a level-set based grid deformation method is presented to construct the adaptive grids around body boundaries. The present scheme is used to simulate steady flow around a semicircular cylinder mounted on the bottom of flow domain and calculated results are validated by results of a body fitted grid method. Finally, present method is applied to a complex flow around multi body and the usefulness is checked by investigating calculated results.

• Journal of Ship and Ocean Technology
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• v.9 no.1
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• pp.38-46
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• 2005

Survivability improvement method for naval ship design has been continually developed. In order to design naval ships considering survivability, it is demanded that designers should establish reasonable damage conditions by air explosion. Explosion may induce local damage as well as global collapse to the ship. Therefore possible damage conditions should be realistically estimated in the design stage. In this study the authors used ALE technique, one of the structure-fluid interaction techniques, to simulate air explosion and investigated survival capability of damaged naval ships. Lagrangian-Eulerian coupling algorithm, equation of the state for explosive and air, and simple calculation method for explosive loading were also reviewed. It is shown that air explosion analysis using ALE technique can evaluate structural damage after being attacked. This procedure can be applied to the real structural design quantitatively by calculating surviving time and probability.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.375-382
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• 2003

Porous media consist of physically and chemically different materials and have an extremely complicated behavior due to the different material properties of each of its constituents. In addition, the internal structure of porous media has generally a complex geometry that makes the description of its mechanical behavior quite complex. Thus, in order to describe and clarify the deformation behavior of porous media, constitutive models for deformation of porous media coupling several effects such as flow of fluids of thermodynamical change need to be developed in frame of Arbitrary Lagrangian Eulerian (ALE) description. The aim of ALE formulations is to maximize the advantages of Lagrangian and Eulerian methods, and to minimize the disadvantages. Therefore, this method is appropriate for the analysis of porous media that are considered for the behavior of solids and fluids. First of all, governing equations for saturated porous media based on ALE description are derived. Then, weak forms of these equations are obtained in order to implement numerical method using finite element method. Finally, Petrov-Galerkin method Is applied to develop finite element formulation.

• Transactions of Materials Processing
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• v.3 no.2
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• pp.156-166
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• 1994

An arbitrary Lagrangian-Eulerian (ALE) finite element method has been developed. The finite element formation is derived and implemented for rigid-viscoplastic materials. The developed computer program is applied to the analysis of axisymmetric square die extrusion, which has many difficulties with updated Lagrangian approach. The results are compared with those from updated Largrangian approach. The results are compared with those from updated Lagrangian finite element program. Updating scheme of time dependent variables and mesh control are also examined.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.2
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• pp.108-115
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• 2016

In this paper, fluid-structure of interaction behavior of a fluid-filled cylindrical polymer container impacted by a high speed spherical projectile was studied using ALE(Arbitrary Lagrangian Eulerian) method. The hydrodynamic ram phenomenon occurred by the impact projectile penetrating through the container was investigated by examining time histories of projectile velocity and fluid pressure and density. The analysis results were agreed reasonably well compared to those by experiments.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.2
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• pp.286-290
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• 2008

This paper summarizes the components of an explicit aeroelastic solver developed especially for the simulation of dynamic fracture events occurring during the flight of solid propellant rockets. The numerical method combines an explicit Arbitrary Lagrangian Eulerian (ALE) version of the Cohesive Volumetric Finite Element (CVFE) scheme, used to simulate the spontaneous motion of one or more cracks propagating dynamically through a domain with regressing boundaries, and an explicit unstructured finite volume Euler code to follow the flow field during the failure event. A key feature of the algorithm is the ability to adaptively repair and expand the fluid mesh to handle the large geometrical changes associated with grain deformation and crack motion.

• Structural Engineering and Mechanics
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• v.6 no.2
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• pp.173-183
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• 1998

In the shape design of flexible structures, it is useful to predict the initial shape from the desirable large deformed shapes under some loading conditions. In this paper, we present a numerical procedure of an initial shape determination problem for hyperelastic materials which enables us to calculate an initial shape corresponding to the prescribed deformed shape and boundary condition. The present procedure is based on an Arbitrary Lagrangian-Eulerian (ALE) finite element method for hyperelasticity, in which arbitrary change of shapes in both the initial and deformed states can be treated by considering the variation of geometric mappings in the equilibrium equation. Then the determination problem of the initial shape can be formulated as a nonlinear problem to solve the unknown initial shape for the specified deformed shape that satisfies the equilibrium equation. The present approach can be implemented easily to the finite element method by employing the isoparametric hypothesis. Some basic numerical results are also given to characterize the present procedure.

• Journal of the Society of Naval Architects of Korea
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• v.41 no.1
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• pp.23-30
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• 2004

In the Lagrangian vortex particle method based on the vorticity-velocity formulation for solving the incompressible Navier-Stokes equations, a numerical scheme for calculating pressure fields is presented. Implementation of the numerical method is directly connected with the well-established surface panel methods, just by dealing with the dynamic coupling among vorticity field. Assuming the vorticity and the velocity fields are to be calculated in time domain analysis, the pressure calculation for a complete set of solution at present time step is performed in a similar way to the one used in the Eulerian description. For a validation of the present method, we illustrate the early development of the viscous flow about an impulsive started circular cylinder for Reynolds number 550. The comparative study with the Eulerian finite Volume method provides an extensive understanding and application of the mesh-free Lagrangian vortex methods for numerical simulation of viscous flows around arbitrary bodies of general shape.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.173-176
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• 2009

The Arbitrary Lagrangian-Eulerian(ALE, in short) method is the new description of continum motion, which combines the advantages of the classical kinematical descriptions, i.e. Lagrangian and Eulerian description, while minimizing their respective drawbacks. In this paper, the ALE description is adapted to simulate fluid-structure interaction problems. An automatic re-mesh algorithm and a fluid-structure coupling process are included to analyze the interaction and moving motion during the 2-D axisymmetric solid rocket interior FSI phenomena simulation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.10 s.253
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• pp.1235-1241
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• 2006

A new hydrocode which is still under development using Lagrangian, Eulerian and arbitrary Lagrangian-Eulerian operators, has been described. The three operators are implemented into a single framework by incorporating the sequential three stages of Lagrangian, remesh and remap stages. Several numerical schemes used for each operator are discussed briefly in this paper. In order to evaluate the characteristics of each operator, the Taylor Impact Test has been simulated using each operator and the results are compared. Currently the code is 1st order accuracy in the material interface tracking algorithm and can not handle multimaterial in the mixed cell. The areas of possible enhancement of the code are also discussed.