Application of Full and Approximate Flow Models in Topology Optimisation of Passive Cooling for Electronics Cabinets

This paper applies a previously developed framework for topology optimisation of passive cooling to a vertically-oriented electronics cabinet with multiple heat generating chips. The flow field in the cabinet is complex due to the buoyancy generated by the multiple chips interacting with each other. Thus, it becomes difficult to intuitively design heat sinks for this application. Therefore, topology optimisation is applied to generate optimised heat sink geometries customised for the actual layout of chips inside the cabinet. Both a full Navier-Stokes flow model and an approximate flow model is applied to the problem. The approximate model is shown to be insufficient on its own for the defined problem and the full model is shown to be computationally expensive and unstable. A hybrid optimisation approach is then applied, using the full model in the beginning to point the optimisation in the right direction and the approximate model in the subsequent stages to fine tune the heat sink designs. The full model is shown to introduce flow-aware features in the heat sink designs, that increase the performance substantially. It is concluded that heat sink designs should be different for each of the chips in the cabinet depending on its location and interaction with the thermal plumes from other chips.