请问大神门，流固耦合出现这种现象是什么原因啊！

******** minimum time step size reached *********
On a restart minimum timestep will be 0.000E+00
node # 3434 has out-of-range velocities
x-velocity= Infinity
y-velocity= Infinity
z-velocity= -Infinity
node # 3435 has out-of-range velocities
x-velocity= NaN
y-velocity= NaN
z-velocity= NaN
node # 3436 has out-of-range velocities
x-velocity= NaN
y-velocity= NaN
z-velocity= NaN