Rupture Dynamics and Buckling Instabilities of Free-Standing Liquid Crystal Bridges and Filaments

• Applicant: Dr. Tanya Ostapenko
• Subject Area: Fluid Mechanics
• Term: from 2014 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 255351155

One-dimensional, free-standing fluid structures are not often found in nature, but may be formed by any material that can overcome capillary (Rayleigh-Plateau) instability. Once this instability is suppressed, long filaments, with length-to-diameter ratios exceeding 1000, may be formed.Earlier reports on free-standing liquid crystal filaments and bridges measured their mechanical, acoustical, and electrical stability. Another important aspect, on which there are few reports, is the effect of instabilities that lead to rupture or cause the filament to buckle under compression stress. Quantitative knowledge of such processes has found necessity in the food industry for controlling large liquid sheets or ropes for mass production.Substances capable of forming stable filaments have some sort of internal structure. The resulting rupture and buckling dynamics are substantially more complicated than those for viscous Newtonian fluids.In this research program, we plan to systematically study the pinch-off, rupture dynamics, buckling instabilities, and flow characteristics of filaments formed from discotic and bent-core liquid crystals. Liquid crystals are unique because their properties depend greatly on the amount of orientational and positional ordering present. This property distinguishes liquid crystals from other viscous non-Newtonian fluids.Some of the questions we seek to answer are as follows:What are the dynamics of the thinning, pinch-off, and rupture process?How do topological defects on and within the bridge or filament evolve during the rupture process? What effect do they have on the rupture process?How do such structuring processes relate to the elastic forces (orientational and positional)?

• DFG Programme: Research Grants