空气流动的简单例子，不符合实际，求修改

466415737

求大师帮看一下哪一步出现问题了？



/PREP7
ET,1,FLUID141   
K,1,0,0,,   
K,2,15,0,,  
K,3,15,3,,  
K,4,0,3,,   
K,5,0,1.9,,
K,6,10,1.9,,
K,7,10,2.7,,
K,8,0,2.7,,
l,1,2   
l,2,3   
l,3,4   
l,5,6   
l,6,7   
l,7,8   
l,4,8     
l,5,1   
AL,1,2,3,4,5,6,7,8
alls
smrt,1
MSHAPE,0,2D
AMESH,all
LSEL,S,,,5
LPLOT
DL,ALL,,VX,4,1
DL,ALL,,VY,0,1
LSEL,S,,,1,4,1
lsel,a,,,6
LPLOT
DL,ALL,,VX,0,1
DL,ALL,,VY,0,1
LSEL,S,,,7,8,1
LPLOT
DL,ALL,,PRES,0,1
/solve
FLDATA8,NOMI,DENS,1.205
FLDATA8,NOMI,VISC,1.8135e-5,
/COM,,STEADY STATE ANALYSIS,0   
FLDATA2,ITER,EXEC,20,
allsel
solve