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Low Mach Number Fluctuating Hydrodynamics for Electrolytes
Physical Review Fluids (2016)
  • Alejandro Garcia, San Jose State University
  • Andy J Nonaka, Lawrence Berkeley National Laboratory
  • John B. Bell, Lawrence Berkeley National Laboratory
  • Aleksandar Donev, New York University
  • Jean-Philippe Peraud, Lawrence Berkeley National Laboratory
  • Anuj Chaudhri, Jawaharlal Nehru Centre for Advanced Scientific Research
We formulate and study computationally the low Mach number fluctuating hydrodynamic equations for electrolyte solutions. We are interested in studying transport in mixtures of charged species at the mesoscale, down to scales below the Debye length, where thermal fluctuations have a significant impact on the dynamics. Continuing our previous work on fluctuating hydrodynamics of multicomponent mixtures of incompressible isothermal miscible liquids [A. Donev et al., Phys. Fluids 27, 037103 (2015)], we now include the effect of charged species using a quasielectrostatic approximation. Localized charges create an electric field, which in turn provides additional forcing in the mass and momentum equations. Our low Mach number formulation eliminates sound waves from the fully compressible formulation and leads to a more computationally efficient quasi-incompressible formulation. We demonstrate our ability to model saltwater (NaCl) solutions in both equilibrium and nonequilibrium settings. We show that our algorithm is second order in the deterministic setting and for length scales much greater than the Debye length gives results consistent with an electroneutral approximation. In the stochastic setting, our model captures the predicted dynamics of equilibrium and nonequilibrium fluctuations. We also identify and model an instability that appears when diffusive mixing occurs in the presence of an applied electric field.
Publication Date
November 18, 2016
Publisher Statement
This article was originally published in Physical Review Fluids, volume 1, issue 7, 2016. ©2016 American Physical Society.

This article is also available online at this link.
Citation Information
Alejandro Garcia, Andy J Nonaka, John B. Bell, Aleksandar Donev, et al.. "Low Mach Number Fluctuating Hydrodynamics for Electrolytes" Physical Review Fluids Vol. 1 Iss. 7 (2016) ISSN: 2469-990X
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