icepak 非一致性网格 nonconformal.ppt

F-1Non-Conformal MeshingF-2•A non-conformal mesh is one where there is transition from many cells to one cell •In Icepak, assemblies of objects can be meshed non-conformally - A “slack” or envelope can be defined around a particular assembly and the resulting region is meshed independent of the mesh outside •This enables embedding a fine mesh within the assembly sub-region without leading to cell bleeding, while the model outside the assembly has a course meshMesh for AssemblyMesh in Main ModelNon-conformal InterfaceNon-Conformal meshing - AssemblyF-3•The first thing to do is to edit the assembly, and turn on the option to mesh separately. •Next, add a “slack” region around the assembly - By default the bounding box of the assembly is the min/max extents of the objects making up the component - Slack region allows the user to re -define the bounding box, to make it slightly larger than the objects making up the component. Assembly – defining slackF-4•The assembly bounding box must have sufficient slack so that its sides do not touch any Icepak object•Cabinet, walls and hollow block are the only objects that may touch the sides of a non-conformally meshed assembly•All objects except conducting thin plates and hollow blocks can intersect an non-conformal assembly – the portion within will be meshed non-conformally•Any object can lie completely within the non-conformal assembly even though it may not be a part of the assemblyRules for non-conformal meshing (1)F-5•For example, in this model a 1U heat sink design is modelled as an assembly - By default the bounding box would be the the size of the base in the x-z dimensions, and extend to the top of the fan casing. - Where the fins touch the default bounding box, there would be a solid cell on the internal side of the interface, and a fluid side on the outside of the interface - this is currently not allowed by the solver - Adequate slack must be specified, as in the figure below, so that the assembly bounding box does not touch the heat sink fins - After specifying the slack the assembly can cut through a solid or fluid object, as the PCB is cut in this exampleRules for non-conformal meshing (2)Bounding Box of AssemblyPCBF-6•Multiple assemblies can be meshed separately provided: - Assemblies are not be embedded within each other •In this instance, choose not to mesh the embedded assembly separately. Then it will be included in the non-conformal interface of the larger assembly. - Assemblies do not touch •So the bounding box of one assembly cannot share a surface with the bounding box of a second assembly - Assemblies do not intersectRules for non-conformal meshing (3)F-7•In this example, either the TO220 can be meshed separately, or the heat sink can be meshed separately, as the bounding box for the TO220 lies inside that for the heat sink - The best option here, is to mesh the heat sink separatelyBounding box for Heat SinkBounding box for TO220Example:F-8•Once the regions have been defined for each assembly, then under the meshing panel, turn on the option to mesh assemblies separately. •Icepak will then mesh the model and embed a finer mesh on the assembly region. •Both the Hexa-Unstructured and Hexa-Cartesian methods can be used to mesh assemblies separately.Conformal Mesh - 111,329 cellsNon-Conformal Mesh - 77,149 cellsMeshing。