Simcenter STAR-CCM+ How to use reports with contact-based interfaces
2023-11-02T03:57:34.000-0400
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Summary
This article discusses how to use reports when working with contact-based interfaces
Details
Contact-based interfaces are part of the larger parts-based approach to setting up a simulation. One of the main ideas of the parts-based approach is to separate geometry-prep & meshing from physics, where the former is handled under Parts and the latter under Regions & Interfaces. One of the main advantages of the parts-based approach is the reduction of nodes under the Regions/Boundaries/Interfaces folders because these nodes contain groups of Parts/Surfaces/Contacts which share common physics. However, it is important to retain a finer level of granularity when doing reporting and post-processing. This article discusses the details of using reports when contact-based interfaces are present in a simulation, but similar ideas apply to visualization as well.
As an example, let's use a conjugate heat transfer simulation of a graphics card.
The graphics card simulation contains 23 solid parts and 3 fluid parts but only 1 solid and 1 fluid region. Additionally, the simulation contains 31 solid-solid contacts and 25 fluid-solid contacts but again only 1 solid-solid interface and 1 fluid-solid interface.
Lastly, make sure not to double-count your results by selecting both the parent surface and some of the child contacts. An example of such a selection is shown below where we are trying to match the total heat flux out of a memory chip to the heat source of 4.0 W applied within the chip.
STAR-CCM+ documentation sections:
As an example, let's use a conjugate heat transfer simulation of a graphics card.
The graphics card simulation contains 23 solid parts and 3 fluid parts but only 1 solid and 1 fluid region. Additionally, the simulation contains 31 solid-solid contacts and 25 fluid-solid contacts but again only 1 solid-solid interface and 1 fluid-solid interface.
The question then becomes what input parts need to be used to report on individual contacts, e.g. - if we want to know the heat flux from GPU into the heatsink or how much heat is dissipated by the PCB into the air. For this reason, Simcenter STAR-CCM+ will sub-divide any surface which participates in a contact-based interface. As shown below, an additional "Surfaces" folder will show the parent surface split by its different contacts, e.g. - Heatsink[GPU/Heatskink] represents those mesh faces on the surface Heatsink which are part of the GPU to Heatsink interface. Additionally, in this convention the label [rem] (i.e. - remainder) identifies those faces which do belong to any contacts.
Here, we have mistakenly selected both the parent surface M1 and all of the child contacts. The result is that our report gives double the value we are expecting.
Heat Transfer of Boundary Heat Transfer on Volume Mesh
Part Value (W)
Components.Memory Chips.Memory Chip 1.M1 3.999929e+00
Components.Memory Chips.Memory Chip 1.M1[Air/M1] 7.904729e-02
Components.Memory Chips.Memory Chip 1.M1[M1/Heatsink] 3.216737e+00
Components.Memory Chips.Memory Chip 1.M1[PCB/M1] 7.041449e-01
Components.Memory Chips.Memory Chip 1.M1[rem] 0.000000e+00
Total: 7.999859e+00
Thus, be careful that your selection matches exactly the desired data by selecting either the parent surface, e.g. - for the total heat flow across the surface including all contacts, or the desired child contact(s), e.g. - for only the heat flow through the selected contact surfaces.
Heat Transfer of Boundary Heat Transfer on Volume Mesh
Part Value (W)
Components.Memory Chips.Memory Chip 1.M1 3.999929e+00
Components.Memory Chips.Memory Chip 1.M1[Air/M1] 7.904729e-02
Components.Memory Chips.Memory Chip 1.M1[M1/Heatsink] 3.216737e+00
Components.Memory Chips.Memory Chip 1.M1[PCB/M1] 7.041449e-01
Components.Memory Chips.Memory Chip 1.M1[rem] 0.000000e+00
Total: 7.999859e+00
Thus, be careful that your selection matches exactly the desired data by selecting either the parent surface, e.g. - for the total heat flow across the surface including all contacts, or the desired child contact(s), e.g. - for only the heat flow through the selected contact surfaces.
STAR-CCM+ documentation sections: