Topology optimization of a pseudo 3D thermofluid heat sink model

•Topology optimization is applied to the design of air-cooled heat sinks.•A pseudo 3D heat sink model comprising a thermally coupled heat sink base plate and thermofluid design layer is presented.•Heat sink designs periodic perpendicular to the flow direction are presented and discussed.•2D and 3D validation simulations with a body-fitted mesh are conducted.•Topology optimized designs are successfully benchmarked against size optimized parallel fin heat sink designs.