Couette test system

An Ex Vivo Flow-Through Couette Test System... 

In this laboratory, an ex vivo test system was developed and utilized to delineate some of the factors affecting thrombus formation on surfaces. The system consisted of a flow-through couette device (Figure 1) placed in an arteriovenous shunt in a dog. The device was designed to allow independent control of blood flow and shear by separate control of the flow rate through the chamber, and of the rotation speed of a central rod, which is coated with the material to be studied. The validation of the method with respect to flow conditions, hematological considerations, and reproducibility has been reported previously (2—4). 

Fig. 7. Schematic representation of examples of test geometries used. Open systems channel, rotating disc (Hoyt 1972, 1986). Closed systems pipe flow, couette- or searle-systems (Kulicke 1986)...

Used for glass, sol-gels, blood, polymers, etc. The cup-and-bob types define the volume of sample to be sheared in a test cell. The torque needed to achieve a particular rotational speed is measured. The two geometries are known as the Couette or Searle systems the difference depends on whether the cup or bob rotates. The cup can be a cylinder. 

The Wolf and Swift method has been tested on model systems with known Lyapunov spectra and applied to data for the Belousov-Zhabotinskii chemical reaction and Couette-Taylor flow. See refs. [36-37] for a discussion of the requirements on accuracy and the size of a data file. 

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