The Method of Characteristics for Arbitrary Geometry Based on the Customization of Autocad

2008 ◽  
Author(s):  
Qichang Chen ◽  
Hongchun Wu ◽  
Liangzhi Cao
Keyword(s):  
Boundary Condition ◽  
Transport Equation ◽  
Method Of Characteristics ◽  
Complex Geometry ◽  
Interpolation Method ◽  
Neutron Transport ◽  
Outer Boundary ◽  
Neutron Transport Equation ◽  
The Method Of Characteristics ◽  
Selection Of

The method of characteristics (MOC) solves the neutron transport equation along each characteristics line. It is independent of the geometry shape of boundary and region. So theoretically, this method can be used to solve neutron transport equation in highly complex geometry. However, we should describe the geometry strictly and calculate intersect points of each characteristics line with every boundary and region firstly. In complex geometry, due to the great difficulty of treating of the arbitrary domain, the selection of geometry shape and efficiency of ray tracing are limited. So in most of the existing MOC codes, the type of outer boundary is limited as rectangular, hexagonal, triangular or the combination of them. And in order to treat reflective boundary condition, the selection of the azimuthal angles number is not freewill for different outer boundary shapes. To wipe off these limitations for using MOC in more complex fuel assembly calculation, the more powerful geometry treatment method is needed. The geometry treatment through the customization of AutoCAD, famous computer aided design software, is given in this paper. Thanks to the powerful capability of AutoCAD in graphics, the description of complex geometry becomes quite convenient. Moreover, with the language VBA (Visual Basic for Applications), AutoCAD can be customized to calculate intersect points of each characteristics line with every boundary and region. Thereby, no matter how complex or what kind of the geometry shape is, it can be treated uniformly by this method as long as it can be drawn in the AutoCAD. In addition, a directional interpolation method for the treatment of reflective boundary condition is introduced in this paper, so the number of azimuthal angles can be selected freely.

The Powerful Method of Characteristics Module in Advanced Neutronics Lattice Code KYLIN-2

2017 ◽  
Vol 3 (3) ◽  
Author(s):  
Xiaoming Chai ◽  
Xiaolan Tu ◽  
Wei Lu ◽  
Zongjian Lu ◽  
Dong Yao ◽  
...  
Keyword(s):  
Boundary Condition ◽  
User Interface ◽  
Boundary Conditions ◽  
Transport Equation ◽  
Method Of Characteristics ◽  
Neutron Transport ◽  
Diffusion Method ◽  
Graphic User Interface ◽  
Coarse Mesh ◽  
Pressurized Water

Due to powerful geometry treatment capability, method of characteristics (MOC) currently becomes one of the best method to solve neutron transport equation. In MOC method, boundary condition treatment, complex geometry representation, and advanced acceleration method are the key techniques to develop a powerful MOC code to solve complex problem. In this paper, we developed a powerful MOC module, which can treat different boundary conditions with two methods. For problems with special border shapes and boundary condition, such as rectangle, 1/8 of square, hexagon, 1/3 of hexagon, 1/6 of hexagon problems with reflection, rotation, and translation boundary condition, the MOC module adopts periodic tracking method, with which rays can return to start point after a certain distance. For problems with general border shapes, the MOC module uses ray prolongation method, which can treat arbitrary border shapes and boundary conditions. Meanwhile, graphic user interface based on computer aided design (CAD) software is developed to generate the geometry description file, in which geometry is represented by “lines and arcs” method. With the graphic user interface, the geometry and mesh can be described and modified correctly and fast. In order to accelerate the MOC transport calculation, the generalized coarse mesh finite difference (GCMFD) is used, which can use irregular coarse mesh diffusion method to accelerate the transport equation. The MOC module was incorporated into advanced neutronics lattice code KYLIN-2, which was developed by Nuclear Power Institute of China (NPIC) and used to simulate the assembly of current pressurized water reactor (PWR) and advanced reactors, to solve the transport equation with multigroup energy structure in cross sections database. The numerical results show that the KYLIN-2 code can be used to calculate 2D neutron transport problems in reactor accurately and fast. In future, the KYLIN-2 code will be released and gradually become the main neutron transport lattice code in NPIC.

High-Dimensional Model Representations for the Neutron Transport Equation

2014 ◽  
Vol 177 (3) ◽  
pp. 350-360 ◽  
Author(s):  
Zhengzheng Hu ◽  
Ralph C. Smith ◽  
Jeffrey Willert ◽  
C. T. Kelley
Keyword(s):  
Transport Equation ◽  
Neutron Transport ◽  
High Dimensional ◽  
Dimensional Model ◽  
Neutron Transport Equation
Sign in / Sign up

Export Citation Format

Share Document