[Study on a new rheological equation of state for blood].

Blood behaves like a Non-Newtonian fluid under low shear rate. A number of constitutive equations for blood have been proposed in the literature, but yet a general equation which demonstrates all aspects of blood's Non-Newtonian characteristics has not been established. With this problem we analysed the Oldroyd Equation as a possible model for blood. Theory analysis indicated that the phenomena of blood flow under low shear rate, such as shear thinning, stress overshoot and phase delay in periodic flow, can be explained by introducing the equation with four parameters, suggesting it to be an appropriate model for blood. We tested the parameters. Stress versus time curves under rectangular step of shear rate were also tested and the results were compared with those of theory prediction.