Ansys Polyflow’s mesh deformation capabilities allow you to have meshes in your simulation that deform as a result of the flow solution. This capability is used in problems involving free surfaces (for example, an extrusion) and problems involving fluid-structure interactions (for example, a die lip that widens as a result of the flow). This chapter, on the other hand, describes how these capabilities have been extended to allow you to deform the geometry (and the associated mesh) before any flow simulations are run. In other words, you can alter the position and shape of geometric entities (volumes, faces, lines, and points) as part of a preprocessor task. The new mesh in the deformed geometry will have the same number of nodes and will be obtained prior to and independent of any flow calculations. Thus, the deformation applied to your model is strictly the result of user input and is not related to the flow.
The advantages of altering the mesh in a preprocessor task include the following:
There is no need to revisit the mesh generator to perform "slight" modifications to the geometry of your initial mesh.
Depending on how the mesh deformation is defined, it may be possible to apply evolution or user-defined template (UDT) options on the geometric parameters. If evolution is applied on the deformation parameters, a series of meshes will be generated from the initial mesh based on a specific deformation criteria. By applying UDT options, on the other hand, you can save a much smaller version of the data file, which then only allows you to change specified geometric parameters as part of future parametric studies.
Because the mesh deformation is computed using Ansys Polyflow, it is possible to analytically compute the sensitivities of the flow variables with respect to the parameters controlling the mesh deformation.
The mesh generation can be simplified, because the points controlling the mesh deformation can be a node of the mesh and not only a point defined in the mesh generator.
The main applications of this capability include the following:
parametric studies
By prescribing the deformation of the mesh, you can perform a parametric study to evaluate the impact of geometric modifications on different aspects of the flow (for example, pressure drop, stagnation zones, maximum shear rate). This application is described in this chapter.
optimization studies
You can perform an optimization study by allowing the optimizer to find better geometries than the one you originally provided, in order to improve some aspects of the flow (for example, better flow balance at the die exit, reduced pressure drop). This application is described in Optimization.
This chapter provides information about using geometry parameterization to modify the die shape, and contains the following sections: