275632 Modeling of Nanoparticle Motion in an Incompressible Newtonian Fluid: A Comparison Between Fluctuating Hydrodynamics and Generalized Langevin Approaches

Monday, October 29, 2012: 2:15 PM
409 (Convention Center )
Balakrishnan Uma, UPenn, Philadelphia, PA, Portonovo S. Ayyaswamy, Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA, David M. Eckmann, School of Medicine, University of Pennsylvania, Philadelphia, PA and Ravi Radhakrishnan, Department of Bioengineering, University of Pennsylvania, Philadelphia, PA

In order to obtain an accurate description of nanocarrier dynamics in the bloodstream and near wall interactions, we have developed a formalism where both the Brownian motion as well as the hydrodynamic interactions are important. We employ a direct numerical simulation adopting an arbitrary Lagrangian-Eulerian based finite element method to simulate the Brownian motion of nanocarrier in an incompressible Newtonian fluid. Thermal fluctuations are implemented using three different approaches: (1) fluctuating hydrodynamics approach; (2) generalized Langevin approach; (3) a hybrid approach combining (1) and (2) to incorporate memory effects. At thermal equilibrium, the numerical predictions for temperature of the nanoparticle, velocity distribution of the particle, decay of the velocity autocorrelation function, diffusivity of the particle and particle-wall interactions in the presence and absence of adhesive interactions are computed for various flow conditions. We show that the hybrid approach simultaneously preserves the canonical distribution as well as the hydrodynamic correlations.

References:

1.    Nanoparticle Brownian motion and hydrodynamic interactions in the presence of flow fields, B. Uma, T. N. Swaminathan, R. Radhakrishnan, D. M. Eckmann, P. S. Ayyaswamy, Physics of Fluids, 2011, 23, 073602. DOI: 10.1063/1.3611026.

2.  Generalized Langevin dynamics of a nanoparticle using a finite element approach: Thermostating with correlated noise, B. Uma, T. N. Swaminathan, P. S. Ayyaswamy, D. M. Eckmann, R. Radhakrishnan, J. Chem. Phys., 2011, 135, 114104. DOI: 10.1063/1.3635776; Erratum, 136, 019901, 2012.

3.    A hybrid formalism combining fluctuating hydrodynamics and generalized Langevin dynamics for the simulation of nanoparticle thermal motion in an incompressible fluid medium, B. Uma, D. M. Eckmann, P. S. Ayyaswamy, R. Radhakrishnan, Molecular Physics, 2012, in press. (DOI: 10.1080/00268976.2012.663510)

4.  Hybrid scheme combining fluctuating hydrodynamics and generalized Langevin dynamics for nearly neutrally buoyant particle in stationary medium, B. Uma, D. M. Eckmann, R. Radhakrishnan, P. S. Ayyaswamy, ASME Journal of Heat Transfer, 2012, in press.


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