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Electrokinetic Instability in Viscoelastic Fluids in Microgravity Conditionsстатья
- Авторы: Ganchenko Georgy, Popov Vladislav, Ponomarev Roman, Demekhin Evgeny
- Журнал: Microgravity Science and Technology
- Том: 34
- Номер: 5
- Год издания: 2022
- Издательство: C. Hanser
- Местоположение издательства: Germany
- DOI: 10.1007/s12217-022-10000-5
- Аннотация: We examine, with linear stability analysis and direct numerical simulations (DNS), the dynamics of FENE (finitely extensible nonlinear elastic model) fluids in a space between two ion-selective membranes under a potential drop between them. The one-dimensional (1D) solution, describing the quiescent state of the electrolyte, is tested for stability with respect to small sinusoidal perturbations. For Newtonian fluids, the spectrum of the eigenvalues is found to be real and only one root is responsible for the instability. For non-Newtonian fluids, a new branch of the spectrum is found. The most dangerous wavelength is decreasing with increasing of the Deborah number, so the viscoelasticity decreases the characteristic length of perturbations. The DNS of the complete nonlinear system is fulfilled. As the voltage or the Deborah number increase, several instabilities and bifurcations lead to the following nonlinear regimes, replacing each other: spatially periodic steady solutions; spatially and temporally periodic solutions with one time period; spatially and temporally periodic solutions with two time periods; and chaotic solutions. With increasing of the Deborah number or the voltage, the large vortices disappear, while the small ones become the dominant ones. For sufficiently large supercriticality, the nonlinear regimes are characterized by the spike-like charge distribution in the extended space charge region. The spikes are joined by thin flat 1D regions of the space charge. Depending on the regime, these spikes can be steady, oscillating with one period, oscillating with two periods, and oscillating and interacting chaotically. The key mechanism for creating the overlimiting current is related to these spikes.
- Добавил в систему: Демёхин Евгений Афанасьевич