Mesh superposition technique

To reduce this effort, the software Polyflow (Fluent, Lebanon, USA) contains a special module to avoid the remeshing of the flow channel for every single timestep. This is called the Mesh Superposition Technique , where the inner barrel and the screw are meshed separatly. The discrete meshes are overlayed to create one system where the surfaces of the screw define the channel boundary. A major issue with this method is that the flow channel volume varies as the intersection of the surface elements leads to unequal sums over all elements. This is compensated by a compression factor on which the simulation results react very sensitively. 

In the first approach, a numerical model was developed by utilizing the ANSYS POLYFLOW solver in conjtmction with both tire Mesh Superposition Technique and tire Lagrangian adaptive remediing technique to model plunger motion and gob formation... 

For ANSYS POLYFLOW model, the moving parts, such as the plunger, were taken into account utilizing a Mesh Superposition Technique (MST). The geometries and meshes of the... 

Expressions for the limiting shape factors when the width of the channel is small relative to the depth (W H ) are given hy Booy [29]. However, this type of channel geometry is generally not encountered in commercial twin screw systems. Numerical simulation of the flow and heat transfer in twin screw extruders is covered in Chapter 12. Section 12.3.2 discusses 2-D analysis of twin screws, and Section 12.4.3.3 deals with 3-D analysis of flow and heat transfer in twin screw extruders. Since 2000, major advances have been made in the numerical methods used to simulate twin screw extruders. The boundary element method now allows full 3-D analysis of flow in TSEs. A significant advance in the finite element method is the mesh superposition technique that allows analysis of complicated geometries with relative ease. This is discussed in more detail in Chapter 12. 

To create the mixer geometry, a cylindrical mesh is generated for the tank. Two other, completely independent meshes are defined for the blades. The three meshes are then combined into one. As the blades rotate, the transient flow pattern in the tank can be calculated and illustrated by the dispersion of tracer particles, as shown in the figure. As the total number of rotations increases, the tracer becomes more uniformly distributed. After six rotations, the dispersion of the tracer particles in the horizontal plane is satisfactory. Note, however, that the particles have moved little in the vertical direction. This is becanse the anchor impellers in use impart little or no axial momentum to the fluid. Twisted blades, which also impose an axial motion on the flow, might perform better to distribute the tracer throughout the vessel. The mesh superposition technique is well suited to study such systems. For other examples of flow in planetary mixers, see Tanguy et al. (1999) and Zhon et al. (2000). 

Figure 5-28 Dispersion of a particle tracer in a vessel equipped with two intermeshing anchor impellers, calculated using the mesh superposition technique. After six full rotations, the particles are well dispersed on the horizontal plane where they were released.

The mesh superposition technique[6] is used to simphfy the mesh generation of the flow domain(see Fig.l). The elements used were hexahedron elements with 8 nodal points in each element. Material(PE) properties used in the simulation are as follows ... 

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