In this proceeding the demand for a high power density of drives in mobile machinery and their constraints are described. To achieve a high power density with electrical machines liquid cooling is a favoured option. Usually it is state of the art to use cooling jackets in those machines due to manufactureability and robustness. The behaviour of often used rectangular channel structures is well
known and can be described with basic thermodynamics. Possible improvements by using vortex generators inside the channel of a cooling jacket structure are discussed. A basic dimple geometry is shown and also evaluated for a cooling spiral.