Filament yarns for the carpet industry are mainly produced using the BCF process (bulked continuous filament). In this process, the production of the pellets takes place in a single operation via extruder spinning, drawing, texturizing, interlacing and winding. This process offers advantages in terms of efficiency and costs, but has not been able to establish itself in any other market apart from carpet yarn production. The reasons for this are the limitations in terms of the yarn count that can be achieved and the uneven texturing of the yarn. The limiting system component in the BCF process is the texturizing tube. In texturizing tube, the pre-heated yarn is pressed into a compression tube using hot air or steam. A slowly moving lump of compressed and three-dimensionally crimped yarn forms in the texturing tube. If the yarn is heated to just below the melting point at the time of crimping, the crimping effect is significantly enhanced. The crimped yarn is then cooled on a cooling drum. The energy-intensive nature of this process presents an opportunity for optimization. This presentation introduces a flow simulation model for the texturizing tube, with a focus on the interaction between air flow and filaments. The model is developed modularly, dividing the compression chamber into distinct zones, each represented by individual simulation modules. An iterative approach ensures plausibility at every stage, leading to a comprehensive understanding of flow behavior. By capturing these dynamics, the model provides valuable insights into optimizing the BCF process, ultimately enabling more energy efficient designs and more sustainable yarn production. The presentation will be held in cooperation between Institut für Textiltechnik of RWTH Aachen University and KMD Plastifizierungstechnik GmbH.