Abstract
A general relationship between the torque M and the angular velocity \varOmega of a plate is obtained for a time-independent non-Newtonian liquid specified by an arbitrary flow curve. It is assumed that the motion of the liquid is steady and that each liquid particle moves with a constant angular velocity on a circle on a horizontal plane perpendicular to the axis of rotation. The edge effects are neglected. It is shown how to determine the flow curve from the experimental relationship between M and \varOmega for some special cases. Following special cases are considered: i) non-Newtonian liquid obeying power law flow curve, ii) non-Newtonian liquid obeying flow curve expanded into power series, iii) Bingham body. It is shown that the relationship between M and \varOmega for a non-Newtonian liquid obeying power law flow curve is reduced to the well-known formula for a Newtonian liquid when the exponent tends to unity.