Natural and forced conjugate heat transfer in complex geometries on Cartesian adapted grids

The Cartesian incompressible RANS solver with immersed boundaries, IBRANS, recently developed at Stanford, has been extended to include conjugate heat transfer modeling and used for the simulation of the electrical motor of an automotive engine cooling fan system. Such applications are particularly challenging, as they involve very complex geometries with tight tolerances and rotating parts. The new conjugate heat transfer capability of IBRANS has been verified on natural and forced convection flows. The former involves flows in enclosures around a sphere and electronic chips. The latter focuses on heated cylinders for Reynolds numbers covering flow regimes ranging for a steady laminar flow to unsteady turbulent flows. Excellent agreement is achieved with similar simulations with a conventional body-fitted solver (FLUENT 6.1) using equivalent turbulent models. First three-dimensional simulations of the flow and heat transfer within the complete electrical motor are presented. The numerical predictions of the pressure drop through the motor as a function of flow rate agree very well with the measured data over the complete operating range.