characteristic quantities associated with the agitating system. According to Newtons equation of viscosity. viscosity force is (9.1) Where du/dy is velocity gradient and A is the area on which the viscosity force acts. For the agitating system the fluid dynamics involved are too complex to calculate a wide range of velocity gradients present However, it can be assumed that the average velocity gradient is proportional to agitation speed n and the area A is to D2, which results (9.2) he drag force Fp can be characterized in an agitating system ascharacteristic quantities associated with the agitating system. According to Newton’s equation of viscosity, viscosity force is (9.1) Where du/dy is velocity gradient and A is the area on which the viscosity force acts. For the agitating system, the fluid dynamics involved are too complex to calculate a wide range of velocity gradients present. However, it can be assumed that the average velocity gradient is proportional to agitation speed N and the area A is to D2 I , which results. (9.2) The drag force FD can be characterized in an agitating system as A dy du FV = ( ) 2 FV  NDI