Die swell
= Die swell
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= Extrudate swell
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A polymeric extrudate can expand sideways after leaving a die as the <normal-stress differences> and stored deformation generated upstream relax. Axial elastic recovery contributes to transverse swelling in an <incompressible flow>. A Newtonian extrudate can also swell through rearrangement of its velocity profile, so observing swelling alone does not isolate the elastic contribution.