POLYFLOW Key Features
Complex Rheology
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Among commercial CFD providers in the marketplace today, POLYFLOW offers the widest suite of complex rheology models. The generalized non-Newtonian models include the well-known power law, Cross, Bird-Carreau. Carreau-Yasuda, Bingham, Herschell-Bulkley laws, together with temperature difference modifications including the Arrhenius, Fulcher, and Williams-Landel-Ferry (WLF) laws. Differential viscoelastic models include the Giesekus-Leonov, Phan-Thien Tanner, Pom-Pom, FENE-P (for finitely extensible nonlinear elastic fluids) models. The KBKZ integral viscoelastic model is also available. Customized functions can be selected to simulate strain hardening, polymer aging, and thixothropy.
Free Surface Modeling (ALE)
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POLYFLOW is able to handle very complex free surface deformation (using an arbitrary Lagrange-Eulerian, or ALE technique) in 2D and 3D as well as for shell deformation during blow molding and thermoforming processes. Powerful remeshing techniques and an adaptive remeshing method ensure that the quality of the mesh is maintained, even when very large deformations occur.
Contact Detection
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Advanced algorithms in POLYFLOW are able to detect the contact between a deforming free surface (whether a shell or a 2 D or 3D free surface) and a moving solid mold. The evolution of the thickness of the blown or thermoformed product can be calculated during the whole process. Before the contact is detected, advanced adaptive meshing methods investigate the geometry of the mold in the vicinity of the forthcoming contact. The mesh is then adjusted to better handle fine contact with geometrical details.
Fluid Structure Interaction
Because of the high viscosity of some polymers flowing across a thin slit, such as a coat hanger die, the stress and possibly the deformations induced by the flowing polymer or glass cannot always be neglected. POLYFLOW is able to calculate the thermo-mechanical stress and deformation in the solid by coupling structural analysis with CFD. The POLYFLOW approach is fully coupled, ensuring rapid convergence when compared to traditional FSI methods.
Mesh Superposition Technique
Analyzing the flow of materials through a twin screw extruder or surrounding any other solid moving part is a great challenge, since it combines the rotational motion of the screw together with the fluid flowing through the region, often with tight clearances. In addition, generating a mesh for such complex geometry can usually take days. POLYFLOW offers an elegant, simple, and robust technique making use of overlapping mesh regions. A grid is generated for each screw or solid moving part and a different mesh is created for the barrel, where the materials can flow. These meshes are superimposed by means of a POLYFLOW module. An intelligent algorithm detects whether a nodes is inside the moving solid domain or in the flow region. In this manner, the Navier-Stokes equations are solved only in the flow region. Combining this method with an adaptive meshing technique guarantees a high accuracy of the results while maintaining the simplicity of the method. This technique can only be used with fully filled extruders.
GUI Embedded Expert System
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Material flows involving complex rheology, a deforming free surface and other physics such as contact detection and FSI are challenging. In order to assist you during the problem setup and convergence phases, an expert system is available to offer guidance. This expert system recommends numerical strategies to follow according to the physics that has been specified. Once the simulation is done, a diagnostic is proposed for running similar simulations faster in the future, or to facilitate the convergence in similar, yet more difficult cases. The expert system is embedded in a modern Windows-like environment.