The issue of the flow rate of oil during this disaster has become a central issue for primarily two reasons: (1) directing the response requires knowing where the oil where surface and which shores it wash up on and (2) determining which technologies can be used to seal the well depends critically on knowing the flow rate. On May 20, Admiral Allen created the Flow Rate Technical Group (FRTG) to address the question of oil flow rate. Prof. Wereley was appointed a member of this team. After a month of calculations and deliberations over various flow scenarios, the FRTG determined that the most likely flow rate of oil was 35,000 to 60,000 bbl/day of oil only, not including methane or other gaseous hydrocarbons. The FRTG primarily used videos shot by remote operated vehicles (ROVs) because very little other instrumentation was available. The videos were analyzed by various methods to estimate the flow rate of the oil. A number of members of the FRTG used particle image velocimetry (PIV) codes to track the coherent structures at the outer surface of the oil jet to determine its speed. From the surface speed of the jet, the average speed of the jet had to be estimated. There is considerable uncertainty in this step. While the body of jet flow literature spans at least 100 years, the particular scenario here is unique: two phase flow of a heated, immiscible, opaque flow of different properties ejecting into an unbounded reservoir. The literature provided some guidance on what the relationship was between the outer structure speed and the average speed of the jet but this relationship remains the reason that the range between the upper and lower bounds of the flow rate estimate represents nearly a factor of 2.
What is proposed here is a set of laboratory experiments that would as closely as possible replicate the actual situation of oil flowing into sea water. Video would be taken of the flows and analyzed in a manner similar to the FRTG's procedure. Because the experiments are conducted in a lab, the average flow rate of the oil jet will be known and a very good idea of the relationship between the outer surface feature speed and the average jet speed can be found.
The intellectual merit of this activity is two-fold. First, a new method for stand-off analysis of oil spills will be given a solid theoretical base. Second, the physics of a specific class of jets will be explored.
The broader impacts of this activity are considerable. The nearly factor of 2 range on the current flow rate estimate of 35,000 to 60,000 bbl/day are excessively large and due, in large part, to the uncertain relationship between the outer trackable, coherent structure speed and the average speed of the jet. The goal of the work here is to considerably narrow this range. Having a more precise knowledge of the oil spill flow rate is critical to directing the oil spill response both in the on-going disaster and in future disaster which are certain to happen.
