Edit Mesh
Usage of Edit Mesh tools
-To diagnose and fix any problems and improve mesh quality
-To convert element types
-Refine and/or coarsen mesh
-Manual and automatic tools
-For imported as well as internally created mesh
Mesh Checks
To diagnose mesh associativity problems
-Errors–most likely to cause problems in:
Solver translation
Solver input
Solution convergence/run
-Possible Problems – “Unclean surface mesh”
Unwanted elements
Unwanted holes/gaps
May result in incorrect solution
-Can check any combination of errors/possible problems at any one time
Individually select
Click on Error or Possible Problems tabs will select all options in column – selecting again will de-select all
Set Defaults will select most commonly seen/detrimental diagnostics
-Check Mode
Create Subsets–creates a subset of elements that fit each criteria
Check/Fix Each–offers automatic fixing of indicated problem
Mesh Checks: Mesh Errors
-Duplicate Elements
Elements that share all nodes with other elements of the same type
-Uncovered Faces
Volumetric element faces that are neither attached to the face of another volumetric element nor to a surface element (boundary face)
-Missing Internal Faces
Volumetric elements that are adjacent to another of a different part with no surface element between them
-Periodic Problems
Inconsistency in the number of nodes/faces between periodic sides
Special check for rotating (sector) or translational periodic grids
-Volume Orientation
Left handed elements due to incorrect connectivity (node numbering of cell)
-Surface Orientations
Volume elements that share the same surface element (overlap)
-Hanging Elements
Line (bar) elements with a free node (node not shared by another bar)
-Penetrating Elements
Surface element(s) that intersect or penetrate through other surface elements
-Disconnected Bar Elements
Bar elements where both nodes are unattached to other bars
Mesh Checks: Possible Problems
-Multiple Edges
Surface elements with an edge that shares three or more elements
Can include legitimate T-junctions
-Triangle Boxes
Groups of 4 triangles that form a tetrahedron with no actual volume element inside
-2 -Single Edges
Surface element with 2 free edges (not shared by another surface element)
-Single-Multiple Edges
Surface element with both free and multiple edges
-Stand-Alone Surface Mesh
Surface elements that don't share a face with a volumetric element
-Single Edges
Surface elements with a free edge
Can include legitimate hanging baffles
-Delaunay Violation
Tri elements with nodes that are within the circumsphere of adjacent elements
legacy quality criteria
-Overlapping Elements
Continuous set of surface elements that occupy the same surface area (surface mesh that folds on to itself)
-Non-manifold vertices
Vertices whose adjacent elements’ outer edges don't form a closed loop
Typically found in tent-like structures where surface elements jump from one surface to another across a narrow gap or sharp angle
-Unconnected Vertices
Vertices that are not connected to any elements
Usually eliminated automatically upon saving the mesh
Mesh Checks
If Create Subsets was selected
-Will go through all checked criteria at once
-Elements that have a particular error/problem are put into a subset with that diagnostic type name
-Subsets activated in Model Tree
.Turn off all parts or shells to view subsets
If Check/Fix Each was selected
-Will be prompted with options one criteria at a time
Fix: Automatically fix the error/problem
-Recommended only for Duplicate Elements, Volume Orientations, Periodic Problems, Overlapping Elements
Create Subset
Ignore
-For example, multiple edges may be legitimate t-junctions; single edges – legitimate free edges
Mesh Smoothing
Automatically improve element quality
-All element types
-Necessary to have geometry loaded
-Nodes are moved to improve the element quality
Automatic node movement constrained by node projection type to geometry type – e.g. curve nodes will be constrained to move only on curves
-Histogram is automatically displayed/updated after smoothing
User chooses:
-Criterion
-Smooth Mesh Type
Smooth: Element types actively smoothed; quality of type appears as part of histogram.
Freeze: Nodes are held in place during the smoothing process; elements not in histogram
Float: Nodes can be moved along with adjacent smoothed elements, but quality ignored; not shown in histogram
Example: Freeze Prisms and Pyramids while smoothing Tetra. Float surface elements
Advanced Options
-Smooth Parts/Subsets
Smooth all parts, visible parts (activated in model tree), or visible subsets
Quick, local smoothing
-Laplace smoothing
Gives more uniform mesh size relative to neighboring elements
Recommended for TRI only – smooth Tetra after with Laplace turned off
Recommended prior to prism generation
-Not just worst 1%
Factors in all elements instead of only the worst 1% of those beneath quality value and their neighbors
-Violate geometry
Unconstrain nodes slightly from geometry within user defined tolerance – absolute or relative to minimum edge length of mesh elements
Output
ANSYS ICEMCFD Allows you to write input files for many CFD and FEA solvers. The output tab can be used to,
-Select solvers
-Define boundary conditions
-Edit parameters
-Write input file
Wing Edit Workshop
Compute Mesh
http://www.cadfamily.com/html/Article/Mesh%20Preparation%20and%20Output%20to%20Solver_719_1.htm
http://www.cadfamily.com/html/Article/Mesh%20Preparation%20and%20Output%20to%20Solver_719_2.htm
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