The value of relax_zone may be changed, as long as spec_bdy_width = spec_zone + relax_zone.Can be used with periodic_x in tropical channel simulations.

• %23%23%23 对于缓冲区的平滑（我这么翻译的，我也把这个区域叫过渡区域，请版主纠正一下这样说对不对？）