Simulating hydrodynamics in a spring-fed estuary using a three-dimensional unstructured Cartesian grid model

2012 ◽  
Vol 115 ◽  
pp. 246-259 ◽  
Author(s):  
XinJian Chen
Keyword(s):  
Three Dimensional ◽  
Cartesian Grid ◽  
Grid Model

Segregation Patterns and the Phase-Field 3D-Model for Adiabatic Phase Transition in Al-Cu Alloys

2013 ◽  
Vol 668 ◽  
pp. 870-874
Author(s):  
Heng Min Ding ◽  
Tie Qiao Zhang ◽  
Lv Chun Pu
Keyword(s):  
Dendritic Growth ◽  
3D Model ◽  
Three Dimensional ◽  
Cartesian Grid ◽  
Solute Diffusion ◽  
Solute Redistribution ◽  
Cu Alloys ◽  
Solid Phases ◽  
Solid Liquid ◽  
Liquid And Solid Phases

In the paper, a model basing on solute conservative in every unit is developed for solving the solute diffusion equation during solidification. The model includes time-dependent calculations for temperature distribution, solute redistribution in the liquid and solid phases. Three-dimensional computations are performed for Al-Cu dendritic growth into an adiabatic and highly supersaturated liquid phase. A numerical algorithm was developed to explicitly track the sharp solid/liquid (S/L) interface on a fixed Cartesian grid. Three-dimensional mesoscopic calculations were performed to simulate the evolution of equiaxed dendritic morphologies.

Application of a Cartesian-Grid Immersed Boundary Method to 3D In-Cylinder Flow

2012 ◽  
Author(s):  
Claudia Günther ◽  
Matthias Meinke ◽  
Wolfgang Schröder
Keyword(s):  
Level Set ◽  
Immersed Boundary Method ◽  
Three Dimensional ◽  
Cartesian Grid ◽  
Distance Functions ◽  
Immersed Boundary ◽  
Splitting Algorithm ◽  
Signed Distance ◽  
Boundary Method ◽  
Cylinder Flow

In this work, a Cartesian-grid immersed boundary method using a cut-cell approach is applied to three-dimensional in-cylinder flow. A hierarchically coupled level-set solver is used to capture the boundary motion by a signed distance function. Topological changes in the geometry due to the opening and closing events of the valves are modeled consistently using multiple signed distance functions for the different components of the engine and taking advantage of a level-set reinitialization method. A continuous discretization of the flow equations in time near the moving interfaces is used to prevent nonphysical oscillations. To ensure an efficient implementation, independent grid adaptation for the flow and the level-set grid is applied. A narrow band approach and an efficient joining/splitting algorithm for the level-set functions minimize the computational overhead to track multiple interfaces. The ability of the current method to handle complex 3D setups is demonstrated for the interface capturing and the flow solution in a three-dimensional piston engine geometry.

Development of a Household Vacuum Cleaner With a New Cyclone Dust Collector

2007 ◽  
Author(s):  
Shoji Hayashi ◽  
Masatoshi Watanabe ◽  
Yukiji Iwase ◽  
Kyoichi Kanno ◽  
Keiichi Fujimori
Keyword(s):  
High Performance ◽  
Three Dimensional ◽  
Cartesian Grid ◽  
Dust Collector ◽  
Grid System ◽  
Vacuum Cleaner ◽  
Pressure Losses ◽  
Stepped Surfaces ◽  
Cyclone Dust Collector ◽  
High Performance Computers

A household vacuum cleaner named “Tatsumaki cyclone” with a new cyclone dust collector was developed. It has a unique horizontal layout called the inverted cyclone layout that features a dust bunker adjacent to a cyclone cylinder with an up-draught airflow. It also has a new airflow arrangement called triple-suction airflow that separates airflow after removing dust at the cyclone cylinder. The main suction airflow is exhausted from the main port (which is downstream of the cyclone cylinder) through an inner cylinder. The sub-suction airflow is exhausted from the dust bunker after it heavily compresses the dust (sub port). The center suction airflow is exhausted from the center port. In this study, we used the Cartesian grid system to simulate the flow field inside the dust collector. This system uses only rectangular parallelepiped meshes; profiles of the dust collector were represented by stepped surfaces of cubic meshes. Each mesh was generated based on whether it was inside or outside the solid body of the dust collector. High-performance computers have recently been used to help generate super-fine meshes that fit closely the smooth shape of a dust collector. The Cartesian grid system has the advantage of being able to quickly generate square-meshes of complex shape that can be converted directly from the CAD data. We simulated the velocity distribution of single-suction, twin-suction and triple-suction models. The single-suction model had only a main port to exhaust airflow, the twin-suction model had a main port, and a sub port, and the triple-suction model had a main port, a sub port, and a center port. In this study, a Cartesian grid system with a finite difference method was used to correct the unsteady three-dimensional flows. After the simulation, we experimented with pressure losses and measured change in air quantity by the dust load of each model. These steps enabled us to develop a new cyclone dust collector called Tatsumaki cyclone as part of a compact household vacuum cleaner with lower pressure loss and a larger capacity dust bunker.

Progressive Surface Reconstruction of Cardiac Anatomy from Sparse and Scattered Points for Heart Mapping Procedure

2020 ◽  
Vol 10 (11) ◽  
pp. 2564-2576
Author(s):  
Yifan Fu ◽  
Rao Fu ◽  
Jing Wang ◽  
Yirong Liu ◽  
Jian Wu
Keyword(s):  
Surface Reconstruction ◽  
Cardiac Computed Tomography ◽  
Three Dimensional ◽  
Reconstruction Algorithm ◽  
Linear Increase ◽  
Mapping Procedure ◽  
Cardiac Computed Tomography Angiography ◽  
Grid Model ◽  
Search Criterion ◽  
Partition Method

In computer aided radiofrequency catheter ablation of the heart, intraoperative three-dimensional reconstruction of the intracardiac cavity is a very important step. In this paper, we propose a point-by-point surface reconstruction algorithm based on scattered points and guarantee the properties of local reconstruction and surface smoothing. The algorithm firstly builds a generic self-adapted grid model to enclose and approximate to the initial sampled points (at least four points) captured from endocardial surface. Then, the grid model is deformed when adding a newly sampled point. To avoid the linear increase of computation with the increasing of the number of points and unbalanced neighborhood, we propose a local region search criterion based on orthogonal least squares and a neighborhood partition method. Such criterion can guarantee selecting the minimum local balanced points to complete each step of grid deformation. Four normal and six abnormal cardiac computed tomography angiography models specific to the left atrium are used to verify our method. The results show that the surface reconstruction errors as well as the reconstruction time per update are smaller than the state-of-theart methods applied to progressive reconstruction using sparse and scattered points. Furthermore, a cardiac phantom of right ventricle is used to verify the 3D surface reconstruction by our method. The experimental results confirm the feasibility of the proposed algorithm in practical operation.

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