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Stretching of fluid filaments to form either drops or broken threads as well as compression to induce bending and/or coiling instabilities are sensitive to filaments geometry, rheology, inertia and surface tension.
In this study, we explore experimentally these various instabilities for viscoplastic model fluids and propose a theoretical analysis of the onset and development of each of them. We will show that plastic dissipation can significantly change the breakup profile of stretched filaments as well as the final helical shape of compressed ones.
Additional direct numerical simulations of stretched and compressed Bingham and Herschel-Bulckley viscoplastic fluids provide a deeper understanding on the non-linear dynamics of the instabilities.
