Using FloTHERM and the Command Center to Exploit the Principle of Superposition
A set of computational analyses was performed for a system level model to show that the principle of superposition can easily be exploited in a new parametric tool called the Command Center (CC), a module that is included with Flomerics software. Thermal superposition implies that the effect of a set of independent sources in an analysis can be studied one by one and a combination of these sources can be added to provide a solution for a system. This implies that the thermal effect of the sources is linearized to enable the superposition principle. For forced convection systems, this assumption is valid for a broad range of boundary conditions whilst for natural convection systems, this principle will only work in a narrow range of source values. The concept of the adiabatic heat transfer coefficient (AHTC) and superposition kernel function (SKF) has been used as a basis for understanding thermal superposition, a very useful tool enabling thermal analysis before the power list for a new design is available. Because CFD solves the physics of flow and heat transfer implicitly for a model, the concept of the AHTC can be used directly without additional analysis methods except for a quick matrix multiplication process. The method in CFD requires that each heat source is activated as a unit value in turn and the results are stored for any number of probed points in the system. These points are then tabulated and post-processed with the actual system heat load to determine the system temperatures. For forced convection systems where radiation and natural convection effects are minimal, the results of this study have shown excellent correlation.
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