1. Orientation mechanisms

The aim of this section is to show qualitatively how fibers orient themselves in flow. To visualize movement, we work at room temperature with transparent fluids representing the behavior of polymers in the liquid state, such as viscoelastic silicone oils. Various transparent devices can be used.

• In shear flow

  Such a flow can occur, for example, in mold feed channels, or in the cavity itself, when the thickness and width of the flow are constant.

  With a Newtonian fluid, a fiber undergoes periodic rotational motion, the period of which is inversely proportional to the shear rate, and roughly proportional to the fiber's aspect ratio (figure 1 a )