迭代了5000多步，突然发散怎么回事？湍能耗散率最大是多少？

guohf00001

我用的是雷诺应力模式RSM，定常求解，Courant number仅给了0.5。在初始化时，湍能耗散率很大，超出了Solution limits所给的范围，我把它调大了。迭代了5000多步后，出现错误：
divergence detected - temporarily reducing Courant number to 0.005
and trying again...
divergence detected - temporarily reducing Courant number to 0.0005
and trying again...
time step reduced in 1 cells
temperature limited to 5.000000e+03 in 6 cells on zone 2   5383 5.2912e-02 5.4628e+02 6.3481e+02 4.0602e+03 8.0075e+01 1.0000e+00 1.1951e-04 5.5877e-05 6.3541e-05 2.2176e+14 2.2183e+14 2.2177e+14 735:17:34 99095
reversed flow in 16 faces on pressure-outlet 4.

divergence detected - temporarily reducing Courant number to 0.05
and trying again...
divergence detected - temporarily reducing Courant number to 0.005
and trying again...
divergence detected - temporarily reducing Courant number to 0.0005
and trying again...
divergence detected - temporarily reducing Courant number to 5e-05
and trying again...
Error: Internal error at line 842 in file ';rp_mstage.c';.
divergence detected in AMG solver
Error Object: ()
这是怎么回事？是不是边界条件给的不合理，造成湍能耗散率太大的原因？湍能耗散率最大是多少？
请高手帮忙解决一下。谢谢