Abstract:

A multi-scale thermal analysis approach is demonstrated for mixed and forced convection from discrete heat sources in enclosures. This method involves a sequential two-step "zooming-in" approach to resolve the smaller length scales associated with fine structures of heat sources. The first step is the development of a coarse grid global model, with simplified models of components to evaluate flow blockage and temperature distribution pattern. A fine grid local analysis of the solid(s) of interest is then carried out using thermal information from the global analysis as boundary conditions. Implementation of the approach is conducted for a rectangular enclosure containing a printed wiring board (PWB) populated with plastic quad flat packages (PQFPs). Temperature computations from the multi-scale analysis approach were compared favorably with experimentally measured data for the cases studied. More importantly, this method demonstrated great potential in computational time saving.

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