Ansys Polyflow also offers a remeshing rule called the method of planes. This method is similar to the spine technique and can be considered a 3D generalization of the method of spines. The method of planes has been implemented for 3D extrusion applications (direct and inverse), but it remains limited to small displacements of the free surface. The method is based on the algorithm described below.

First, Ansys Polyflow cuts the 3D domain to be remeshed into a series of 2D slices orthogonal to the direction of extrusion (or topologically normal to the free surface or moving interface). The slicing of the domain lowers by one the geometrical dimension of the remeshing rule: for a 2D spine technique, a one-dimensional rule is used; for a 3D Euclidean technique, a two-dimensional rule is used. Each slice (or plane) is then independently remeshed. This means that mesh deformations cannot occur in the flow direction. Each node belongs to only one slice, which is internally considered a 2D mesh. Information required for this slicing includes the definition of initial and final planes. In each slice, Ansys Polyflow will apply the 2D Euclidean distance method described in Euclidean Method. Figure 16.1: Tangential and Domain Remeshing illustrates how sections will be remeshed.

The method of planes is useful for jet-like free-surface problems, such as extrusions. It is not expensive in terms of CPU time, due to the few additional unknowns it introduces. It inherits the topological generality of the Euclidean distance method, but suffers from the same limitation; it is robust only for relatively small deformations of the initial mesh. For extrusion simulations, the 3D Optimesh technique and streamwise method have been proven to be able to cope with much larger displacements of the boundary. See User Inputs for Remeshing for information about using the method of planes.