Flood water
Gold point: Wilding's 16,000 tons at 40 minutes, the basis of his "12 square feet". The eyewitness timeline fits a smaller opening.
How it works
The hull is a parametric fit to Harland & Wolff's hydrostatics (displacement, waterplane, KB, BM within about 1%), cut into 4,400 vertical columns. Every step integrates buoyancy and flood water over those columns at the ship's actual attitude. Sixteen compartments, split port and starboard and above and below E deck, exchange water through holes, doors and the open E deck using orifice and weir laws. Heave, pitch and roll are integrated as a damped rigid body. Four flow parameters were fitted to the eyewitness timeline; everything in the table above is a prediction.
What it leaves out
Hull girder failure (she broke at about 2:17), pumps, air trapped in compartments, the superstructure's buoyancy, and whatever drove the 10–15° port list witnesses saw: the model only reaches about 6° until the final plunge.