Ferro-hydrodynamics of droplet necking filaments
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| Format: | Preprint |
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2025
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| _version_ | 1866918259231555584 |
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| author | Bera, Neeladri Sekhar Roy, Apurba Dhar, Purbarun |
| author_facet | Bera, Neeladri Sekhar Roy, Apurba Dhar, Purbarun |
| contents | We explore the necking, filament thinning, and pinchoff dynamics of ferrofluid droplets within a magnetic field, via a simple and low-cost experimental method. In our studies, both the Ohnesorge number Oh and the Deborah number De are O1, a typically inaccessible regime with conventional extensional rheometers. Under magnetic forcing, the nanoparticles assemble into field aligned, chainlike structures, that generate a tunable magnetoelastic response, and markedly alter the extensional flow. Although behaving as Newtonian liquids in the absence of a magnetic field, the field induces extensional thickening, and the emergence of beads on a string BOAS structures in the ferrofluid filaments, a non-Newtonian signature. By combining controlled elongation with high speed imaging, we directly quantify the magnetic field-dependent extensional viscosity and relaxation time. Our findings underscore how magnetically induced microstructures govern filament stability and extensional dynamics in ferrofluids. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2512_19459 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Ferro-hydrodynamics of droplet necking filaments Bera, Neeladri Sekhar Roy, Apurba Dhar, Purbarun Fluid Dynamics Soft Condensed Matter Applied Physics We explore the necking, filament thinning, and pinchoff dynamics of ferrofluid droplets within a magnetic field, via a simple and low-cost experimental method. In our studies, both the Ohnesorge number Oh and the Deborah number De are O1, a typically inaccessible regime with conventional extensional rheometers. Under magnetic forcing, the nanoparticles assemble into field aligned, chainlike structures, that generate a tunable magnetoelastic response, and markedly alter the extensional flow. Although behaving as Newtonian liquids in the absence of a magnetic field, the field induces extensional thickening, and the emergence of beads on a string BOAS structures in the ferrofluid filaments, a non-Newtonian signature. By combining controlled elongation with high speed imaging, we directly quantify the magnetic field-dependent extensional viscosity and relaxation time. Our findings underscore how magnetically induced microstructures govern filament stability and extensional dynamics in ferrofluids. |
| title | Ferro-hydrodynamics of droplet necking filaments |
| topic | Fluid Dynamics Soft Condensed Matter Applied Physics |
| url | https://arxiv.org/abs/2512.19459 |