A 1% aqueous solution of polyethylene oxide at 333 K has power law parameters n = 0.6 and rn = 0.50 Pa . sn. The solution is being pumped between two tanks, with the first tank at pressure p, and the second at pressure p,. The pipe carrying the solution has a length of 14.7m and an internal diameter of 0.27 m. It has been decided to replace the single pipe by a pair of pipes of the same length, but with smaller diameter. What diameter should these pipes have so that the mass flow rate will be the same as in the single pipe?