If you added a large pressure change at a domain interface and find that the momentum residuals are oscillating, then you can set the following expert parameter:
ggi ap relaxation = 0.3
Note that this is not in the list of expert parameters listed in Pre, so to add it, use the following steps:
1) Right click on the “Solver” object in the Outline tree and select Insert > Expert Parameter
2) Select one of the expert parameters, but do not change its default settings and press OK
3) Right click on expert parameters and select “Edit in Command Editor”
4) Add ggi ap relaxation = 0.3 and press “Process”