Two engineers, Alice and Bob, are arguing over whether one pipe geometry is better than the other for transferring heat from a process fluid. Alice maintains that a hexagonal pipe rotated $45$ will have a higher Nusselt number while Bob says that an elliptical pipe will perform better. Due to phase change inside of the pipe, the surface of the pipe will be maintained as a constant temperature of $100$C$.$ The incoming flow is of air at atmospheric pressure and room temperature $40$C$,$ with a velocity of $14$ m$/$s crossing over the pipes. Each pipe has a diameter D of $1$ cm$.$ To settle their argument, determine which pipe has the higher Nusselt number.