Ferrofluidic Couette flow in time-varying magnetic field
Despite time-dependent boundary conditions being ubiquitous in natural and industrial flows, to date the influence of such temporal modulations (e.g. with driving frequency O_H) has been given minor attention. The present problem addresses ferrofluidic Couette flow in between counter-rotating cylind...
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| Format: | article |
| Publication Date: | 2022 |
| Country: | España |
| Institution: | Universitat Politècnica de Catalunya (UPC) |
| Repository: | UPCommons. Portal del coneixement obert de la UPC |
| Language: | English |
| OAI Identifier: | oai:upcommons.upc.edu:2117/371817 |
| Online Access: | https://hdl.handle.net/2117/371817 https://dx.doi.org/10.1016/j.jmmm.2022.169205 |
| Access Level: | Open access |
| Keyword: | Taylor vortices Magnetic fluids Nonlinear systems Taylor-Couette flow Ferrofluid Time-varying magnetic fields Non-linear dynamics Instabilities Bifurcation theory Vòrtexs de Taylor Sistemes no lineals Àrees temàtiques de la UPC::Física |
| Summary: | Despite time-dependent boundary conditions being ubiquitous in natural and industrial flows, to date the influence of such temporal modulations (e.g. with driving frequency O_H) has been given minor attention. The present problem addresses ferrofluidic Couette flow in between counter-rotating cylinders in a spatially homogeneous magnetic field subject to time-periodic modulation. Such a modulation can lead to a significant inner Reynolds number (Re_i) enhancement for both, either helical and toroidal flow structures. Using a modified Niklas approximation, the effect of low- and high-frequency modulation onto the primary instabilities, stability boundaries as well as on the non-linear oscillations that may occur is investigated. Focusing on bi-stable co-existing solutions, around their stability thresholds quite complex non-linear system response and flow dynamics is detected. For the system remaining supercritical always a single solution is selected by O_H, while crossing the bifurcation thresholds within a modulation period the triggered system response is more complex, reaching from alternation between different solutions towards the appearance of intermittent behavior. |
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