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The Improved Paving Method
It is a direct quadrilateral gridding method that utilizes the advancing front scheme to generate quadrilateral grids in the computational domain without formation of the background mesh beforehand.
The generated meshes contain few irregular internal nodes and the high-quality elements could follow the boundary of the domain smoothly. In addition, the number of grids is reasonably small to accelerate the calculating speed.
It is a direct quadrilateral gridding method that utilizes the advancing front scheme to generate quadrilateral grids in the computational domain without formation of the background mesh beforehand.
The generated meshes contain few irregular internal nodes and the high-quality elements could follow the boundary of the domain smoothly. In addition, the number of grids is reasonably small to accelerate the calculating speed.
Unstructured Grids Examples
Based on the improved Paving method, the gridding program (Fortran codes) was developed to discretize some irregular domains (as shown in the following figures). Compared with the commercial software, the proportion of high-quality grids could increase by at least 20% and the calculating speed could increase by at least 30% when achieving the same accuracy.
* (a) - Grids generated by the improved Paving method; (b) - Grids generated by the commercial software "Gambit"
Based on the improved Paving method, the gridding program (Fortran codes) was developed to discretize some irregular domains (as shown in the following figures). Compared with the commercial software, the proportion of high-quality grids could increase by at least 20% and the calculating speed could increase by at least 30% when achieving the same accuracy.
* (a) - Grids generated by the improved Paving method; (b) - Grids generated by the commercial software "Gambit"
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Hybrid Grids Generation Method
Both the structured and unstructured grid algorithms have been extensively developed and successfully applied in different fields with their advantageous properties. However, the two algorithms have their own limitations and drawbacks.
Fortunately, the two kinds of algorithms could complement each other with their strengths and the hybrid grids generation method taking advantage of both structured and unstructured grids would be truly attractive.
The hybrid grids generation method includes three main procedures: (1) structured grids generation for subdomains, (2) hole cutting procedure to eliminate overlapped grids and form the hole body, (3) unstructured grids generation to fill the hole body and connect different parts of structured grids.
* (a) - Hole cutting procedure to form the hole body; (b) - Unstructured grids generation
Both the structured and unstructured grid algorithms have been extensively developed and successfully applied in different fields with their advantageous properties. However, the two algorithms have their own limitations and drawbacks.
Fortunately, the two kinds of algorithms could complement each other with their strengths and the hybrid grids generation method taking advantage of both structured and unstructured grids would be truly attractive.
The hybrid grids generation method includes three main procedures: (1) structured grids generation for subdomains, (2) hole cutting procedure to eliminate overlapped grids and form the hole body, (3) unstructured grids generation to fill the hole body and connect different parts of structured grids.
* (a) - Hole cutting procedure to form the hole body; (b) - Unstructured grids generation
New Hybrid Grids Generation Method based on Improved Hole Cutting
Based on the composite structured grid algorithms and previous hybrid grids generation methods, a new hybrid grids generation method with improved hole cutting algorithm was developed to generate hybrid grids which are structured-grid dominated with unstructured grids in a relatively small region.
By the flexible decomposition of external domain and alternate implementation of structured grid generation for internal subdomains and improved hole cutting, the present method avoids the appearance of regions with multiple overlapping grids. Besides that, improved formation of boundaries for unstructured grid generation also enhances the robustness of method.
Figures (a) - (i) clearly show different stages of the alternation of structured grid generation and hole cutting for a curved flow channel containing several independent circles within it and illustrate the desirable features of this improved process.
Based on the composite structured grid algorithms and previous hybrid grids generation methods, a new hybrid grids generation method with improved hole cutting algorithm was developed to generate hybrid grids which are structured-grid dominated with unstructured grids in a relatively small region.
By the flexible decomposition of external domain and alternate implementation of structured grid generation for internal subdomains and improved hole cutting, the present method avoids the appearance of regions with multiple overlapping grids. Besides that, improved formation of boundaries for unstructured grid generation also enhances the robustness of method.
Figures (a) - (i) clearly show different stages of the alternation of structured grid generation and hole cutting for a curved flow channel containing several independent circles within it and illustrate the desirable features of this improved process.
Hybrid Grids Examples
The examples of hybrid grids generation for several typical computational domains demonstrate the promising features of this present method. Specifically, it could successfully generate highly stretched structured grids along the boundaries and guarantee the grid quality for various configurations, especially those with severe changes of geometry.
The examples of hybrid grids generation for several typical computational domains demonstrate the promising features of this present method. Specifically, it could successfully generate highly stretched structured grids along the boundaries and guarantee the grid quality for various configurations, especially those with severe changes of geometry.