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Growing complexity has resulted in an increased computational effort in CFD modeling of electronic systems. To reduce the computational effort, one or several heat sinks can be represented by a compact "porous block" model, with an effective thermal conductivity and pressure loss coefficient. In this study of parallel plate heat sinks in laminar forced convection, a methodology is developed to analytically determine the fluid properties of compact heat sink models that provide acceptable levels of approximation. The results of an extensive set of CFD simulations for a three heat sink channel, covering three distinct heat sink geometries, air velocities from 0.25 m/s to 2 m/s and various spacings between the heat sinks, were used to create and evaluate the effectiveness of compact models. Use of a two term, equivalent loss coefficient-reflecting the linear and quadratic components in the pressure drop of a porous block-has led to good agreement between the detailed numerical and compact model predictions, with compact heat sink pressure drops usually slightly higher (<10%) than detailed heat sink pressure drops.