Rheology  is "the deformation science of materials". It is the study of how materials such as honey, dough, polymers and blood flow under an applied stress or pressure. 

Example

Below is a snapshot of a  composite of fibers and a polymer that is heated to 300C and squeezed between two parallel plates by applying a force. The value of the force and the displacement of the plates can be monitored. In addition by screen printing a grid along the thickness direction of the material, one can monitor the deformation of the grid. Hence, we can gather local (velocity distribution) and global (force, displacement) information from the same experiment 

Velocity Distribution

Velocity distribution in a unidirectional APC-2 laminate during a 0.2 cm/min squeeze flow experiment. 

...after 0s 
...after 40s 
...after 80s 
 

For further information on these experiments and results, you may refer to the following publications 

        S. Shuler and S. G. Advani, "Transverse Squeeze Flow of Concentrated Aligned Fibers in Viscous Fluids, Journal of 
        Non-Newtonian Fluid Mechanics,  65 p. 47-74 (1996) 

        S. Shuler and  S. G. Advani , " Flow Instabilities During the Squeeze Flow of MultiAxial Laminates," J. of Composite 
        Materials   31, pp.2146-2160 (1997). 

        T. S. Creasy and S. G. Advani ,"A Model Long-Discontinuous Fiber Filled Thermoplastic Melt in Extensional Flow", 
         J. of  Non-Newtonian Fluid Mechanics, 73, p.261 (1997) 

        T. S. Creasy , S. G. Advani and R.K. Okine, "Transient Rheological Behavior of a Long Discontinuous Fiber-Melt 
         System,"  J. of Rheology, 40 , pp.497-520 (1996) 

        T. S. Creasy , S. G. Advani and R.K. Okine, "Non-linear Response of a Long Discontinuous Fiber-Melt System in 
        Elongational Flows, Rheological Acta  35 p. 347-355 (1996)