Use a Partition by Expression node (
) to partition 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 Partition by Expression node, right-click a 2D or 3D Mesh or
Mesh Part node (that has an imported mesh) and select
Partition by Expression from the
Intersections and Partitions menu. That menu is also available on the
Mesh toolbar. Then use the sections below to specify the geometric entities to partition, the logical expression, and the condition for division.
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 in the
Logical expression field. For instance, the expression
(x*x+y*y)<1 defines a ball partition in 2D and an infinite cylinder division 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. You can also use the
meshelement variable to partition the mesh. For example, if you know that elements 1 to 10 are a separate domain, write
meshelement<=10 to partition this as a separate domain.
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.
