• Journal of Advanced Research in Ocean Engineering
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• v.4 no.2
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• pp.78-85
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• 2018

This paper presents a study of the effects of the free surface to marine propeller including the mesh effect of the models. In the present study, we conduct the numerical simulation for propeller performance employing the openwater test. The numerical simulations compare the meshing strategies for the propeller and show the effects on both thrust and torque. OpenFOAM is applied to solve the propeller problem and then open water performances of KCS propeller (KP505) are estimated using a Reynold-averaged Navier-Stokes equations (RANS) solver and the turbulence of the $K-{\omega}$ SST model. Unstructured meshes are used in the numerical simulation employing hexahedral meshing for mesh generation. The arbitrary mesh interfacing (AMI) and multiple rotating frame (MRF) are compared to define the best meshing strategy. The meshing strategies are evaluated through 3 classifications, i.e., coarse, medium, and fine mesh. Thus, the propeller can be performed utilizing the best mesh strategy. The computational results are validated by comparison with the experimental results. The $K_T$, $K_Q$, and efficiency of the propeller are compared to an experimental result and for all of the meshing strategies. Thus, the simulations show the influence of meshing in order to perform the propeller performances.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.427-428
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• 2007

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.1 s.173
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• pp.196-205
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• 2000

Computed Tomography (CT), Nuclear Magnetic Resonance Imaging (MR1) and some ultrasound techniques make it possible to obtain cross sections of human body or mechanical parts. In CAD system, a series of sectional surfaces can also be obtained from solid models of 3D objects. In this paper we introduce a tetrahedral meshing algorithm from these series of general sections using basic operators. In this scheme. general sections of three-dimensional object are triangulated first and side surfaces between two sections are triangulated by the use of tiling process. Finally tetrahedral meshing process is performed on each layer of 3D objects, which is composed of two general sections and one side surface.

• Coupled systems mechanics
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• v.4 no.3
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• pp.237-249
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• 2015

In the gear meshing process, gear temperature field concerns the meshing surface friction, the friction heat depends on the contact pressure, the contact pressure is affected by the elastic deformation of gears and the temperature field caused by the thermal deformation, so the temperature field, stress field and displacement field should be mutual coupling. It is necessary to consider in meshing gear pair in the operation process of thermodynamic coupling contact stress (TCCS) and thermodynamic coupling deformation (TCD), and based on thermodynamic coupling analysis (TCA) of gear teeth deformation.

• Journal of the Korea Computer Graphics Society
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• v.18 no.1
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• pp.29-34
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• 2012

High-quality tetrahedral meshes are crucial for FEM-based simulation of large elasto-plastic deformation and tetrahedral-mesh-based simulation of fluid flow. This paper proposes a volume meshing method that exploits an octree-based adaptive signed distance field to fill the inside of a polygonal object with tetrahedra, of which dihedral angles are good. The suggested method utilizes an octree structure to reduce the total number of tetrahedra by space-efficiently filling an object with graded tetrahedra. To obtain a high-quality mesh with good dihedral angles, we restrict the octree in such a way that any pair of neighboring cells only differs by one level. In octree-based tetrahedral meshing, the signed distance computation of a point to the surface of a given object is a very important and frequently-called operation. To accelerate this operation, we develop a method that computes a signed distance field directly on the vertices of the octree cells while constructing the octree using a top-down approach. This is the main focus of the paper. The suggested tetrahedral meshing method is fast, stable and easy to implement.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.6
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• pp.63-68
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• 2015

Recently, 3D printer technologies have been used in many research efforts for high precision manufacturing. In particular, the rapid prototyping technology has been developing rapidly, because it can be manufactured in a short time with a 3D designed shape. This paper relates to the production characteristics of the straight bevel gear designed using a 3D print using the PolyJet method. The characteristics of a 3D printed straight bevel gear were compared with a machined straight bevel gear. The accuracy of the produced straight bevel gear was evaluated by backlash, meshing pattern, face angle, root angle, and surface roughness.

• Journal of Mechanical Science and Technology
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• v.14 no.4
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• pp.408-417
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• 2000

The design and simulation of meshing of a single enveloping worm-gear drive with modified surfaces is presented. Generally worm-gear is generated by the hob which is identical to the worm. This process guarantees the conjugation between the worm and the gear but results in a line contact at every instant which is very sensitive to misalignment. The localization of bearing contact is necessary to reduce the sensitivity of the worm-gear drive to misalignment. Practically this localization is achieved by application of an oversized worm type hob to cut the worm-gear. The oversized hob approach is very practical and effective to localize bearing contact but can not provide the conjugation between the worm and the modified worm-gear. This work proposes an analytical procedure to make the worm surface conjugate to the worm-gear which is cut by the oversized hob. The developed computer program allows the investigation of the influence of misalignment on the shift of the bearing contact and the determination of the transmission errors, the contact ratio and the principle curvatures. The developed approach has been applied for ZK type of single-enveloping worm-gear drives and the developed theory is illustrated with a numerical example.

• 한국전산유체공학회:학술대회논문집
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• 2000.10a
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• pp.86-91
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• 2000

Automatic method for generation of mesh and three dimension natural convection flow result adapted by this method are presented in this paper. It lake long time to meshing com plex 3-D geometries, and It's difficult to clustering grid at surface boundary. Octree structure resolve this difficulty.

• Transactions of Materials Processing
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• v.15 no.3 s.84
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• pp.189-194
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• 2006

In this paper, an automated adaptive mesh generation scheme, based on an advancing-front-Delaunay method, is presented fur finite element simulation of three dimensional bulk metal farming processes. Basic approach is introduced in detail, including a surface meshing and volume meshing technique and a mesh density control scheme. The presented approach is applied to automatic forging simulation in order to evaluate the effect of the developed schemes. Comparison shows a good agreement between required mesh density and generated mesh density, implying that the presented approach is appropriate for automatic mesh generation in metal forming simulation.

• Journal of Mechanical Science and Technology
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• v.15 no.5
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• pp.592-601
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• 2001

An automatic mesh generation scheme with unstructured quadrilateral elements on trimmed NURBS surfaces has been developed. In this paper NURBS surface geometries in the IGES format have been employed to represent geometric models. For unstructured mesh generation with quadrilateral elements, a domain decomposition algorithm employing loop operators has been modified. As for the surface meshing, an indirect 2D approach is proposed in which both quasi-expanded planes and projection planes are employed. Sampled meshes for complex models are presented to demonstrate the robustness of the algorithm.