Global residuals in transient case
 

Once again... I´m wondering how to judge variations in the global residuals in a transient case. Can anyone please tell me how to deal with the fact that after a few hundred iterations the global mass residual does a few "peaks" to a value between 0.1 and 1 and then goes back under the global residual tolerance of 0.001 for the rest of the calculation. Time step and courant nr. should be OK in this case. Thanks mx