Tech Briefs

Laminar Flow in a Tube Bundle

Additional flow-condition-based interpolation (FCBI) elements will be available in ADINA 8.1. These are the 3-node element in 2D, and the 4-node, 5-node and 6-node elements in 3D. The new elements can be used in conjunction with the existing 4-node (2D) and 8-node (3D) FCBI elements. Using mixed FCBI elements is particularly useful for meshing irregular surfaces and volumes. The triangles (2D), tetrahedra, pyramids and wedges (3D) are also useful for modeling transition regions between fine and coarse meshes.

The animation above depicts the pathlines in a 2D bundle of tubes with laminar flow. A constant velocity boundary condition is prescribed at the inlet and no-slip condition is imposed on the tubes. This problem demonstrates the use of mixed elements, with a mesh that is composed of triangular and quadrilateral FCBI elements, seen in greater detail below. The triangular elements are used in the transition between the fine and coarse mesh.