SU2 divergnece due to BUFFET value
 

Dear members
Greetings
I am working on compressible flow over airfoil with a flap of zero thickness in 2d.
after generating grid in pointwise when running the simulation in su2, it is diverging and on probing the data i found that BUFFET column in history file is having "nan" since very first iteration.
can anyone please share a thought over it as why such divergence is occurring .
thanks in anticipation.
regards
chandan