Second, the free-boundary is handled by using combination of the zero-velocity method with the general ghost-image method and fourth-order difference format is used in free-boundary.

然后采用将零速度法和广义虚像法相结合的方法来处理自由边界，并在自由边界上采用四阶精度差分格式；

youdao

Second, the free-boundary is handled by using combination of the zero-velocity method with the general ghost-image method and fourth-order difference format is used in free-boundary.

然后采用将零速度法和广义虚像法相结合的方法来处理自由边界，并在自由边界上采用四阶精度差分格式；

youdao