Spreading of Carbopol gels

This work aims to study flows within a wedge at the inclination angles in the 5°–20° range. Flow within a wedge occurs when a Carbopol solution is pulled horizontally by a moving conveyer belt through the wedge apex opening at different speeds. The upper side of the wedge is fixed at the exit by a pivot joint about which it could rotate. At the wedge entrance, a force gauge is placed so that it is pushing at the upper side of the wedge to keep it at a predetermined position (and thus at a predetermined inclination angle). The gauge measures the restraining force required to counteract the pressure buildup on the flowing Carbopol solution side and to keep the upper side of the wedge at its position. Visualization through the transparent vertical sides of the wedge was used to track seeding particles inside the solution to reconstruct the velocity profile and in particular to reveal plug flow regions characteristic of the yield stress liquids.