Creating Rectilinear Meshes for LS-DYNA¶
Most of the meshes used in first-pass FEM simulations of acoustic
radiation force excitations are large rectangular solids with either
uniform cubic 3D elements, or elements with a slight aspect ratio. This
document provides an overview of the process of generating a 3D mesh
using tools in this repository (fem/mesh).
Syntax¶
mesh/GenMesh.py will generate a the rectilinear mesh with
user-specified properties. You can specify two opposing corner vertices
of the mesh (--n1 and --n2), the element density on each edge
(x, y, z), and the names of the output files for node and element
definitions.
Run: python GenMesh.py --help for detailed input syntax.
Coordinate System¶
Meshes in this code base utilize different conventions for the FEM portion of the code compared to the Field II simulation component. LS-DYNA mesh conventions are:
x - elevation
y - lateral
z - axial (negative, with transducer face @ z = 0)
Maintaining a right-hand rule convention, for a quarter-symmetry model, x would span a negative range of values for positive 7 values.
Units¶
The typical unit system for the mesh is CGS, and this will be assumed in the code that passes data to/from Field II.
Next Steps¶
Your mesh will be used as an input to Field II to simulate the acoustic radiation force at nodes. This is done using
field/field2dyna.You will need to generate boundary conditions for your mesh (
mesh/bc.py)You may want to create structures in your mesh with different material properties (
mesh/CreateStructure.py)