Modeling large-scale electronic systems using computational fluid dynamics through a "zoom-in" approach

This paper talks about Computational Fluid Dynamics (CFD) modeling of large-scale electronic systems like telecommunication racks using a "zoom-in" approach. FLOTHERM™ was used as the CFD tool for this work. Zoom-in modeling, a two-step process, involves focusing on a critical element, or a subsystem rather than the whole system. This is much more efficient because such small-scale models are easier to build and troubleshoot, faster to solve, and more accurate. The aim of this paper is to outline the methodology involved in zoom-in modeling using a complex telecommunications rack as the vehicle. First, the telecommunication rack was modeled at the system level using two approaches: (a) representation of detailed boards as bulk resistances to flow with heat dissipation, (b) lumping of components on the board to a few major components. This first-stage analysis led to the identification of a critical board in the system. The second step involved zooming-in on the critical board by modeling it in complete detail using the thermal and flow boundary conditions obtained from the system level model. Finally, a detailed system level model was solved for comparison of the component temperatures and near-component flow details with the zoom-in model results.