Index

Remeshing technique

Ver: 3
 

DESCRIPTION

For flow problems with free surfaces and/or moving interfaces, since a part of the boundary (free surface and/or moving interface) is deformed, the finite element mesh should also be deformed. The remeshing is defined in the part of the domain of the current sub-task which needs to be remeshed.

For 2-D flows, five remeshing techniques are available :
 

(1) The 'THOMPSON TRANSFORMATION' : a Thompson transformation is built upon a global coordinates system specified by the user.

(2) The 'SPINES' technique : the moving part of the domain is remeshed along logical lines, which are oriented normal to the free surface or interface.

(3) The 'EUCLIDIAN METHOD' technique : this is a global remeshing based on the Euclidean distance.

(4) The 'THIN SHELL METHOD' : this remeshing algorithm has been developed for handling the large mesh deformations and nodal displacements which are encountered in blow moulding and thermo-forming applications. A tangential remeshing is applied to one of the free surfaces of the shell, in order to keep an acceptable element distribution into the mesh. The internal nodes are relocated along spines which are defined as being geometrically normal to the master free surface.

(5) The 'OPTIMESH-2D' technique : this is a remeshing based on force equilibrium principle : mesh segments act as elastic bars and vertices as articulations generating reactive torques. This technique requires the same boundary conditions than Thompson transformation.

(6) The 'THIN SHELL METHOD + LAGRANGIAN MASTER' technique : this method combines the 'Thin Shell' method with a Lagrangian motion of the master. It means that, along the master surface, nodes of the finite element mesh correspond to material points. Interior nodes are relocated using the Optimesh technique, but at the end of each time step.

(6) The 'LAGRANGIAN ON THE BORDER ONLY' technique : this method combines the 'Optimesh-2D' method with a Lagrangian motion of the borders of the remeshing domain.. It means that, along the borders, nodes of the finite element mesh correspond to material points. Interior nodes are relocated using the force equilibrium principle of the Optimesh technique.
 

 For 3-D flows, four remeshing techniques are available :
  (1) The 'THOMPSON TRANSFORMATION' : a Thompson transformation is built upon a global coordinates system specified by the user.

(2) The 'METHOD OF PLANES' : this consists of applying the EUCLID remeshing in logical planes, which are oriented normal to the free surface or interface.

(3) The 'THIN SHELL METHOD' : this remeshing algorithm has been developed for handling the large mesh deformations and nodal displacements which are encountered in blow moulding and thermo-forming applications. A tangential remeshing is applied to one of the free surfaces of the shell, in order to keep an acceptable element distribution into the mesh. The internal nodes are relocated along spines which are defined as being geometrically normal to the master free surface.

(5) The 'OPTIMESH-3D' technique : in 3-D, this method combines the planes technique with optimesh. In the classical planes technique, the mesh is cut into slices and a 2-D remeshing (Euclid) is applied to each section. In the current technique, Optimesh 2-D is applied to each section.

(6) The 'LAGRANGIAN' technique : in 3-D, available in transient simulations with shell models only. In this method, the nodes of the finite element mesh correspond to material points.
 

 There are, in addition, the following two options :
  (-2) Adaptive section for prediction : this option allows to specify the adaptive section for inverse prediction.

(-1) Constant section for prediction : this option allows to specify the constant section for inverse prediction.

  SEE ALSO