POLYFLOW - Initial boundary conditions at the inlet (orientation, anisotropy, stretching) for the DCPP model in film casting?
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What is the definition of the stretching variable (in words)? What typical values can be imposed Anisotropy factor s. If s=1 along a certain direction, this means that all the material is aligned along this direction. If s = 0, this means that there is no specific orientation (or no anisotropy). However, one shouldkeep in mind that right before the die exit in film casting, the material has mainly undergone a shear flow; under normal shear conditions, the resulting anisotropy is moderate, so that s = 0.1 is already a good choice... Stretching variable at a mikroscopic level, the stretching variable is the ratio of the current length of the molecule to the initial one. In shear flow, stretching is often very moderate. Now, the word "moderate" has to be understood objectively: the number can be small, but it may have already a significant meaning in the physics! |
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