$useperiodicboun

$useperiodicboun is the command to assign the periodic boundary point. In 3D-DDCC, you need to assign the periodic point in your boundary condition

Command format is as following:

$useperiodicboun
periodic_point_filename 

For example

$useperiodicboun
Micro_LED.msh.periodic.txt

The fileformat of periodic_point_filename should be

N_num
Point_1   point_1_p
Point_1   point_1_p
Point_1   point_1_p
Point_1   point_1_p
Point_1   point_1_p
....
....  N_num lines.  

For example: for the mesh grid as following, the left and right hand side are periodic boundary

01---02---03---04---05
|    |    |    |    |
06---07---08---09---10
|    |    |    |    |
11---12---13---14---15
|    |    |    |    |
16---17---18---19---20
|    |    |    |    |
21---22---23---24---25

The file format of Micro_LED.msh.periodic.txt would be

5
1  5
6  10
11 15
16 20
21 25