Use a Logical Expression node () to split geometric entities of an imported mesh by creating at least one new geometric entity for the elements that fulfill the specified logical expression.

To add a Logical Expression node, right-click a 2D or 3D Mesh node (that has an imported mesh) and select Logical Expression from the Partition Entities menu. Then use the sections below to specify the geometric entities to split, the expression, and the split condition.

Define the geometric entities that you want to split. You choose the geometric entity level from the Geometric entity level list:

Enter a logical expression using x, y, or z (3D only); the mesh size h and mesh quality qual* (see Mesh Element Quality and Size); Unary, Binary, and List Operators and Their Precedence Rules; and Mathematical and Numerical Constants. For instance, the expression (x*x+y*y)<1 defines a ball split in 2D and an infinite cylinder split in 3D. You can also use the Boolean variables istri, isquad, istet, ispyr, isprism, or ishex in the expression in order to partition the mesh according to the respective element type (triangular, quadrilateral, tetrahedral, pyramid, prism, or hexahedral, respectively). For instance, the expression istet makes a separate domain for each connected set of tetrahedra, while the expression ispyr || ishex makes a separate domain for each connected set of elements containing pyramids or hexahedra.

Use the Include element if expression is fulfilled for list to select the condition for which the logical expression is fulfilled for an element. Choose All vertices to make an element satisfy the expression if it is true for all element vertices, or choose Some vertex if it is true for at least one element vertex.