An optical technique for determination of rheological properties of gelatin

The rheological behavior of ballistic gelatin is studied experimentally by a newly developed optical technique for visualization of gelatin flow between two parallel plates at high shear rates in the range of 2000/s–8000/s. The unsteady motion of this fluid is captured by the displacement profiles of grid lines marked on the gelatin specimen. By utilizing a power-law model for fluid behavior and then solving the unsteady momentum equation of the non-Newtonian fluid, the power-law model parameters have been determined for early part of the shear flow where linearity assumption in velocity profile is valid. The exponent in the power-law model was found to be 2.25 ± 0.43. The diffusion profiles from optical images also compare well with numerical predictions based on extracted rheological properties of gelatin. Finally, it was noted that the model results compare well with those obtained from other experimental methods on the same gelatin material and also with other fluids using similar experimental methods.