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LaGriT Los Alamos Grid Toolbox Carl Gable meshing.lanl.gov lagrit.lanl.gov

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LaGriT Mesh Generation Mesh Optimization Geometric Computing Element and Node Set Manipulation IO, Boundary Conditions, Initial Conditions

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LaGriT: Mesh Generation Delaunay point connection –2D triangulation –3D tetrahedralization

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LaGriT: Mesh Generation 2D arbitrary (concave) polygon triangulation

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LaGriT: Mesh Generation Block structured i,j,k connectivity 2.5D Stacking of z(x,y) surfaces 2x5 3x2

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LaGriT Mesh Optimization Refine –edge, face, element –Rivara Refine –field value, field gradient, aspect ratio, volume, arbitrary point

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LaGriT Mesh Optimization Derefine –edge length, volume, aspect Original Elements Filter: Remove small area and high aspect ratio elements while maintaining geometry.

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LaGriT Mesh Optimization Smooth –elliptic, laplace, random Massage - refine-derefine-smooth

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LaGriT Geometry Constructive Solid Geometry surface/s_a/intrface/cylinder/x1,y1,z1/x2,y2,z2/radius surface/s_b/intrface/cylinder/x1,y1,z1/x2,y2,z2/radius surface/s_c/intrface/box/xmin,ymin,zmin/xmax,ymax,zmax/ region/r_ring/gt s_c and gt s_b and le s_a

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Element Element Intersection Mesh-Mesh Element Intersection –Determine elements of mesh_a that are intersected by mesh_b mesh_a mesh_b

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LaGriT Geometric Computing pointlinetriquadtetpyrhex point XXXXXXX line XXXXXX tri XXXXXX quad XXXXXX tet XXXXXX pyr X hex XXXXXX Mesh-Mesh Element Intersection –Compute intersection of mesh_a with mesh_b Mesh-Mesh Intersection –Compute the line of intersection between two triangulated surfaces in 3D space

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Example: Mesh-2-Mesh Intersect Intersect fault surfaces with mesh to select elements to be refined with quadtree type refine.

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LaGriT Element and Node Set Manipulation Point and Element Sets: PSET, ELTSET –Attribute: le,lt,ge,gt,eq,ne e.g. nodes/elements with saturation > 0.5 –Geometry: xyz, rtz, rtp e.g. nodes/elements inside a box, cylinder, sphere –Region e.g. identify all nodes/elements inside a region –Logical: union, intersect, not e.g. nodes/elements inside a sphere and saturation > 0.5 e.g. nodes/elements inside a sphere or saturation > 0.5

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LaGriT Element and Node Manipulation Commands Translate Scale Rotate: rotatept, rotateln Filter Perturb Remove Multi-Key Sort Reorder KDTree Search

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LaGriT Grid Attributes Real and integer node and element attributes Element area, element volume aspect ratio, dihedral angle, solid angle, min/max edge length ratio Identify Sliver, Wedge, Needle, Cap Unit normal, area normal vector Synthetic normal to surface nodes Volume/Area integration of floating point node or cell attributes Dual mesh connectivity Voronoi and median volume and face area

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LaGriT Output Options PyLith GeoFEST FEHM AVS, GMV, Tecplot STL, FLAG, X3D

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Mesh Manipulation Extract Lower D - 3D – 2D – 1D –Volume, Face, Line Extract 2D Surface (plane, isosurface, arbitrary triangulation) from 3D mesh Extract Line (well bore) from 3D mesh

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Mesh Manipulation Extract 2D Surface (plane) from 3D mesh.

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Example: Mesh-2-Mesh Interpolate Source mesh with attribute defined on nodes. Sink mesh with attributes interpolated from source mesh. Nodes in sink mesh outside source mesh are identified. 0,0

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Example Mesh-2-Mesh Interpolation Voronoi – Nearest Point Integer Interpolation Colors of fine quad mesh indicate nearest node of low resolution points.

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Same Geometry, Different Mesh Method

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METIS Interface Supports METIS mesh partition algorithm calls Partition: metis /partition/ metis_partmeshnodal / node / 32 metis /partition/ metis_partmeshdual / dual / 32 Reorder: metis / reorder / metis_edgend / dual metis / reorder / metis_nodend / node

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What is the LaGriT Interface? Command Line Driven Control File Driven Call from Fortran, C, C++ Data structures can be accessed and manipulated by user Developer interface for extension and user modules Platforms: Linux, Mac, Sun, SGI

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What LaGriT Is Not No GUI interface No advancing front algorithm No interface for ACIS, Autocad, … CAD Not unstructured hex mesh (see Cubit)

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Southern California Earthquake Center (SCEC) Community Fault Model (CFM) Landers Hector Mine ~54km EW ~60km NS ~17km Z

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Finite Element Mesh With CFM Landers & Hector Mine Faults Tet Aspect Ratio Tetrahedral Finite Element MeshTetrahedral Finite Element Mesh 340km EW, 360km NS, 124km Z340km EW, 360km NS, 124km Z Element size ~50km far fieldElement size ~50km far field Element size ~500m near faultsElement size ~500m near faults

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Mojave Block Model Original Block Triangles Filtered Block Triangles: Remove small area and high aspect ratio elements while maintaining geometry.

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LaGriT meshing.lanl.gov lagrit.lanl.gov

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