FEATool Multiphysics
v1.14
Finite Element Analysis Toolbox

FINDBDR Find boundary indices for an expression.
[ BDR, INDB ] = FINDBDR( SIN, S_EXPR, MATCH_ALL ) Evaluates S_EXPR for boundary nodes in the grid or fea struct and returns the boundary numbers BDR (corresponding to values in grid.b(3,:)) for which the expression is true, and also indices INDB to the corresponding boundary segments (columns in grid.b). The flag MATCH_ALL requires all nodes on a boundary to fulfill S_EXPR to return the found indices (default). If MATCH_ALL is false all indices to all boundaries BDR, edges, and faces INDB are returned.
1) Set boundary number 2 on all boundary edges/faces where x>0.5. [~,indb] = findbdr( grid, 'x>0.5', false ); b(3,indb) = 2;