6SigmaET Tips & Tricks: Switch Grid Rules When Solving at Different Scales

26 July, 2017

One of the features that sets 6SigmaET apart from other thermal simulation software is its automated gridding. Each intelligent object ‘knows’ how much grid it requires, whether it be a PCB, Component or Heatsink etc. The grid generated for each type of object is based on a set of grid rules defined by our engineers based on a vast wealth of experience in using CFD to model electronics cooling. What many users may not know is that a variety of different grid rules are available, each designed to optimise the grid when solving at a specific scale.

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So what are the different sets grid rules? They are: ‘Big Models’, ‘Package’ ‘Small Models’ and, the default, ‘Grid Rules’. The ‘Big Models’ rule set is most appropriate when modelling solids several metres in size. Background grid is coarsened along with grid in solids, this keeps the cell count manageable for faster solving.  ‘Big Models’ would be the best choice when modelling something large like an electronic billboard.  

‘Package’ rules allow subcomponents to be gridded down to 1 micron. This should only be used when creating incredibly detailed models of IC components.

The ‘Small Models’ rule grids PCB’s, TIM’s, components, heatsinks and solid obstructions down to 0.01m. This allows the intricacies of hand held devices such as mobile phones to be resolved sufficiently.

And what about the default rules? These are designed to be quite versatile. They are appropriate for anything between ‘Big’ and ‘Small’, which can be anything from a server to a cabinet and anything in-between.

How do you change to a different set of rules? It’s quite simple. First decide which is most appropriate for the equipment you’re modelling using the guide above, then go to Solution Control > Grid > Grid Rules Definition File and select accordingly. 

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By: Matt Evans, Product Engineer