(1) Is the calculation implicit or explicit ?  implicit

(2) Did you change operating density from default ? no  

(3) Are you considering surface tension ? no

(4) Is the gravity direction set properly ?  -9.81 in Y-direction

(5) Is the volume fraction at the boundaries (also backflow VF at outlets) set properly ?  VF set to zero at both inlet and outlet.  

(6) Which p-v scheme you are using ? SIMPLE,  PRESTO! And bounded second order implicit transient formulation

(7) What time step size have you set ?  0.01 size, 100 steps

(8) Have you checked the patched domain before calculation ?  everytime, after I initialize

(9) Did you change the advanced stability controls (velocity limiting etc) ?  no

(10) And finally, are you trying to simulate something unphysical ?  no

Note* continuity residual skyrockets toward end of calculation when “floating point exception” occurs (please see attached pic)