流固耦合加了没反应，计算的时候提示这种问题：
NUMBER OF FSI ELEMENT FACE FLAGS SET = 0
以下是命令流：
/clear
/PREP7
ET,1,29 ! 耦合单元
ET,2,29,,1 ! 空气单元
ET,3,42
! 设置材料属性
RHO=1.2041
C0=343.24
Z0=RHO*C0
! 定义空气的密度和声速。
MP,DENS,1,RHO
MP,SONC,1,C0
! 绘制几何模型
K,1,0,0,0
K,2,200,0,0
K,3,200,200,0
K,4,0,200,0
L,1,2
L,2,3
L,3,4
L,4,1
a,1,2,3,4
! 划分网格
TYPE,3
MAT,1
REAL,
ESYS, 0
SECNUM,
!*
ESIZE,5,0, ! 网格尺寸
MSHAPE,0,2D
MSHKEY,1
CM,_Y,AREA
ASEL, , , , 1
CM,_Y1,AREA
CHKMSH,'AREA'
CMSEL,S,_Y
!*
AMESH,_Y1
ALLS
! 改变单元性质
NSEL,S,LOC,X,80,120
NSEL,r,LOC,Y,160,180
ESLN
TYPE,2
EMODIF,ALL
ALLS
NSEL,S,LOC,X,80
NSEL,r,LOC,Y,160,180
NSEL,a,LOC,X,120
NSEL,r,LOC,Y,160,180
NSEL,a,LOC,y,160
NSEL,r,LOC,x,80,120
NSEL,a,LOC,y,180
NSEL,r,LOC,x,80,120
ESLN
TYPE,1
EMODIF,ALL
ALLS
NSEL,S,LOC,X,80
NSEL,r,LOC,Y,160,180
NSEL,a,LOC,X,120
NSEL,r,LOC,Y,160,180
NSEL,a,LOC,y,160
NSEL,r,LOC,x,80,120
NSEL,a,LOC,y,180
NSEL,r,LOC,x,80,120
ESLN
SF,ALL,FSI
SFELIST,ALL,FSI
