In later phases of the development of a cooling system, more information becomes available. Quite often CFD models of the underhood region provide detailed insight regarding the air flow. These CFD models already include the cooling package information from the initial cooling system design (see Initial cooling system). The typical approach is to perform isothermal CFD simulations and use the resulting mass flows to calibrate the 1D KULI model. Moreover the nonuniform velocity profiles on the radiator surfaces can be used by KULI using the CFD interface of KULI advanced cfd. The KULI model is used to calculate the temperatures and heat flows in the cooling package.
This information can then be used in CFD to update the 3D model. A dedicated porosity calculator ensures that the 1D KULI model and the 3D CFD model use the same resistance for the cooling package.