7.6 Effect of viscosity on power requirements A cylindrical bioreactor of diameter 3m has four baffles. A Rushton turbine mounted in the reactor has a diameter onethird the tank diameter and is operated at a speed of 90rpm. The density of the fluid is approximately 1gcm3. The reactor is used to culture an anaerobic organism that does not require gas sparging. The broth can be assumed Newtonian. As the cells grow, the viscosity of the broth increases. (a) Compare power requirements when the viscosity is: (i) approximately that of water; (ii) 100 times greater than water; and (iii) 104 times greater than water. (b) When the viscosity is 1000 times greater than water, estimate the power required to achieve turbulence