(174k) Unidirectional Large-Amplitude Oscillaltory Shear FLOW of Blood

Blood is non-Newtonian suspension of red and white cells, platelets, fibrinogen and cholesterols in Newtonian plasma. This work considers a newly proposed blood test, unidirectional large-amplitude oscillatory shear flow (UD-LAOS). In the laboratory, we generate this by superimposing LAOS onto steady shear flow in such a way that the shear rate never changes sign. It is thus intended to best represent the flow in veins and arteries. Normal stress differences from blood can be used as indications of unhealthy blood, such as sickled cells. UD-LAOS can bring out these normal stress differences, including other non-Newtonian behaviors. To model blood, we consider the most versatile Oldroyd 8-constant framework. We arrive at exact analytical expressions for stress responses. After fitting the Oldroyd 8-constant framework to experimental results, we further use these expressions to predict normal stress difference responses.