Tool grinding is a fundamental process step when manufacturing cylindrical cemented carbide tools. A deeper understanding of the relationship between heat generation, heat transfer and fluid dynamics is essential to optimize the application of cooling lubrication. Due to the porous structure of the grinding tool as well as the rough surfaces of tool and workpiece, this inherently leads to multiscale problems. In this paper, an approach for modeling the heat transfer between the grinding tool, the workpiece and coolant on the microscale and mesoscale is introduced, including the effective influence of the porous structure. As a basis for the simulations, experimental investigations are conducted using individual abrasive grains. A linear relationship between the single grain chip cross section and the tangential force is established with an average RMSE of 1.421 N, allowing the total heat flux to be calculated. The results are then transferred to continuous and discontinuous 2D multiscale fluid dynamic simulations in order to predict heat generation and to potentially optimize the cooling lubrication in grinding processes.