Fem-bem coupling methods and systems for sliding contact interface

A computer readable medium containing instructions for controlling a computer system for performance of numerically simulating physical phenomena of an electromagnetic rail-gun having a pair of parallel rails and a projectile located therebetween by a method comprising:

• receiving, in a computer system, a description file of a finite element method (FEM) model representing a projectile and a pair of parallel rails;
• generating a boundary element method (BEM) mesh, representing ambient air surrounding the rails and the projectile, from the FEA model, the BEM mesh being configured with a gap caused by a sliding contact interface between the projectile and each of the pair of parallel rails;
• conducting a time-marching simulation using the FEM model and the BEM mesh, the time-marching simulation includes a plurality of solution cycles in which a coupled FEM-BEM procedure is conducted;
• at each solution cycles, removing a plurality of BEM faces that are in contact with one another and associated nodes and edges;
• and creating a plurality of new triangular BEM faces in accordance with a set of rules to patch a gap as a result of the removed BEM faces, the gap is located along each contact interface within the BEM model;
• and
• storing the time-marching simulation's results into a file on a storage device and graphically displaying the results in a monitor upon user's instruction after the time-marching simulating has ended, whereby the storage device and the monitor are coupled to the computer system.

A system for numerically simulating physical phenomena of an electromagnetic rail-gun having a pair of parallel rails and a projectile located therebetween, the system comprising:

• a main memory for storing computer readable code for at least one application module;
• at least one processor coupled to the main memory, said at least one processor executing the computer readable code in the main memory to cause the at least one application module to perform operations by a method of:
• receiving a description file of a finite element method (FEM) model representing a projectile and a pair of parallel rails;
• generating a boundary element method (BEM) mesh, representing ambient air surrounding the rails and the projectile, from the FEA model, the BEM mesh being configured with a gap caused by a sliding contact interface between the projectile and each of the a pair of parallel rails;
• conducting a time-marching simulation using the FEM model and the BEM mesh, the time-marching simulation includes a plurality of solution cycles in which a coupled FEM-BEM procedure is conducted;
• at each solution cycles, removing a plurality of BEM faces that are in contact with one another and associated nodes and edges;
• and creating a plurality of new triangular BEM faces in accordance with a set of rules to patch a gap as a result of the removed BEM faces, the gap is located along each contact interface within the BEM model;
• and
• storing the time-marching simulation's results into a file on a storage device and graphically displaying the results in a monitor upon user's instruction after the time-marching simulating has ended.