07-mesh - Lecture 7 Meshing Applied Computational Fluid...

Info icon This preview shows pages 1–10. Sign up to view the full content.

1 Lecture 7 - Meshing Applied Computational Fluid Dynamics Instructor: André Bakker © André Bakker (2002-2006) © Fluent Inc. (2002)
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

2 Outline Why is a grid needed? Element types. Grid types. Grid design guidelines. Geometry. Solution adaption. Grid import.
Image of page 2
3 Why is a grid needed? The grid: Designates the cells or elements on which the flow is solved. Is a discrete representation of the geometry of the problem. Has cells grouped into boundary zones where b.c.’s are applied. The grid has a significant impact on: Rate of convergence (or even lack of convergence). Solution accuracy. CPU time required. Importance of mesh quality for good solutions. Grid density. Adjacent cell length/volume ratios. Skewness. Tet vs. hex. Boundary layer mesh. Mesh refinement through adaption.
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

4 Geometry can be very simple... … or more complex geometry for a “cube” Geometry The starting point for all problems is a “geometry.” The geometry describes the shape of the problem to be analyzed. Can consist of volumes, faces (surfaces), edges (curves) and vertices (points).
Image of page 4
5 Geometry creation Geometries can be created top-down or bottom-up. Top-down refers to an approach where the computational domain is created by performing logical operations on primitive shapes such as cylinders, bricks, and spheres. Bottom-up refers to an approach where one first creates vertices (points), connects those to form edges (lines), connects the edges to create faces, and combines the faces to create volumes. Geometries can be created using the same pre-processor software that is used to create the grid, or created using other programs (e.g. CAD, graphics).
Image of page 5

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

6 Typical cell shapes Many different cell/element and grid types are available. Choice depends on the problem and the solver capabilities. Cell or element types: 2D: 3D: triangle ( “tri” ) 2D prism ( quadrilateral or “quad” ) tetrahedron ( “tet” ) pyramid prism with quadrilateral base ( hexahedron or “hex” ) prism with triangular base ( wedge ) arbitrary polyhedron
Image of page 6
7 node face cell face cell node edge 2D computational grid 3D computational grid cell center Terminology Cell = control volume into which domain is broken up. Node = grid point. Cell center = center of a cell. Edge = boundary of a face. Face = boundary of a cell. Zone = grouping of nodes, faces, and cells: Wall boundary zone. Fluid cell zone. Domain = group of node, face and cell zones.
Image of page 7

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

8 Grid types: structured grid Single-block, structured grid. i,j,k indexing to locate neighboring cells. Grid lines must pass all through domain. Obviously can’t be used for very complicated geometries.
Image of page 8
9 Different types of hexahedral grids.
Image of page 9

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Image of page 10
This is the end of the preview. Sign up to access the rest of the document.
  • Fall '10
  • N/A
  • Mesh, Unstructured grid, Skewness Cell Quality

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern