Zipper Layer Method for Multi-Block Mesh Connectivity
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Solution Overview
Problem
Existing methods for joining multi-block structured meshes, particularly in complex geometries like turbomachinery, face challenges such as node misalignment, interpolation errors, and loss of conservative properties, leading to inefficient mesh generation and inaccurate flow predictions.
Innovation Solution
The Zipper Layer Method creates an unstructured interface layer between multi-block structured meshes by overlaying surfaces, identifying and merging matching mesh points, projecting points to align mesh lines, and generating an unstructured mesh of triangles and quadrilaterals, eliminating hanging nodes and high-aspect-ratio tetrahedra, thus allowing direct connection without interpolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If non-matching interface approach is used to join multi-block meshes, then mesh generation flexibility is improved, but interpolation errors occur and conservative properties are lost
Solution Approach 1:
The patent introduces an unstructured mesh interface layer as an intermediary between two structured multi-block meshes. This interface layer acts as a mediator that can accommodate node misalignment and geometric mismatches while maintaining conservation properties through direct face-to-face connectivity, thereby resolving the contradiction between flexibility and accuracy.
Solution Approach 2:
The patent creates a composite mesh structure combining structured meshes (for bulk regions requiring high accuracy) with an unstructured mesh interface layer (for flexible connection). This composite approach allows each region to utilize the strengths of its mesh type, resolving the contradiction by having structured meshes provide accuracy and the unstructured interface provide flexibility.
2Adaptability or versatility
If Chimera mesh technique is used to handle complex geometries, then geometric complexity is managed, but accuracy reduces due to interpolation errors
Solution Approach 1:
The unstructured mesh interface layer serves as an intermediary that eliminates the need for interpolation between overlapping structured blocks. By providing direct connectivity through the interface, it maintains conservation properties and accuracy while still enabling complex geometry representation.
Solution Approach 2:
The patent extracts the interface region from the structured mesh and replaces it with an unstructured mesh layer. This extraction removes the problematic interpolation operations that occur in Chimera techniques, thereby maintaining accuracy while preserving the ability to handle complex geometries.
3Stability of the object's composition
If buffer layers with unstructured techniques are used to fill gaps, then mesh continuity is achieved, but poor quality elements are generated in high-aspect-ratio regions
Solution Approach 1:
The patent applies local quality control by generating the unstructured mesh interface layer with specific attention to element quality in critical regions. The interface layer is constructed to avoid high-aspect-ratio tetrahedra in tip gaps and other sensitive regions, while still achieving mesh continuity across the interface.
4Extent of automation
If fully unstructured meshes are used to produce meshes for complicated geometries, then mesh generation automation is improved, but numerical accuracy and computational efficiency decrease
Solution Approach 1:
The patent segments the mesh into three distinct regions: structured multi-block meshes for bulk regions (providing high accuracy and efficiency), an unstructured mesh interface layer for connection (providing automation and flexibility), and maintains this segmentation throughout the domain. This segmentation allows each region to be optimized for its specific function.
Solution Approach 2:
The patent creates a composite mesh structure where structured meshes (for numerical accuracy) are combined with an unstructured interface layer (for automation). This composite approach allows the majority of the domain to use accurate structured meshes while the automated unstructured interface handles the complex connection requirements.
Data Source
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Figure 2b
Figure 2c
AI summary
A method of connecting three-dimensional structured meshes to form a conformal mesh, for solutions of flow problems, comprising: - forming an interface by overlaying surfaces of two structured meshes; - defining an interface set of mesh points in the interface; - merging mesh points in the interface set that are within a predetermined distance of each other and projecting mesh points of one mesh in the interface that are within a predetermined distance of a line of the other mesh; - generating an interface layer in the form of an unstructured mesh; and - inserting a node at the centre of each hexahedra, and producing an unstructured layer of cells between the two structured meshes by joining the nodes to the mesh points of the interface layer. This method ensures a thin unstructured layer with no hanging nodes.