To increase the understanding of the complex flow phenomena in high-speed wave and energy-transfer screws, an experimental screw simulator was designed and manufactured in my bachelor thesis in the form of a double slit die with alternating, sinusoidal height profiles. The present work deals with the theoretical and experimental investigation of the screw simulator. Furthermore, a CFD simulation was carried out to compare the numerical and experimental results. In the experimental part, tests were carried out to determine the influence of the following parameters: (i) geometry of the flow channels, (ii) material properties, and (iii) processing conditions. The geometry of the flow channels being adjustable, the channel height and the clearance were changed. The materials, which were used in the experimental procedure, include a low viscosity film grade (PP-RD204CF) and a high molecular weight pipe grade (HDPE HE3493 LSH). As a further variable parameter, the operation mode of the extruder was changed, on the one hand, the synchronous operation (same speed) and the asynchronous operation (different speed of both extruders). The investigations showed that due to the wave profile of the flow channels, even at the same rotational speed of the extruder an overflow of the plastic melt occurs. This overflow is enhanced by increasing a speed of an extruder or using low viscosity materials. These experimental findings should also be validated by mathematical calculation and CFD simulation. Another advantage of CFD simulation lies in the simple visualization of flow phenomena, mixing processes and rapid flow analysis with different process parameters. Based on the comparisons it could be shown that simulation as well as semi-numerical computation are a high-quality approximation of the experimental investigations.