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Numerical modeling of an all vanadium redox flow battery

Clausen, Jonathan C.; Martinez, Mario J.; Brunini, Victor B.; Moffat, Harry K.

We develop a capability to simulate reduction-oxidation (redox) flow batteries in the Sierra Multi-Mechanics code base. Specifically, we focus on all-vanadium redox flow batteries; however, the capability is general in implementation and could be adopted to other chemistries. The electrochemical and porous flow models follow those developed in the recent publication by [28]. We review the model implemented in this work and its assumptions, and we show several verification cases including a binary electrolyte, and a battery half-cell. Then, we compare our model implementation with the experimental results shown in [28], with good agreement seen. Next, a sensitivity study is conducted for the major model parameters, which is beneficial in targeting specific features of the redox flow cell for improvement. Lastly, we simulate a three-dimensional version of the flow cell to determine the impact of plenum channels on the performance of the cell. Such channels are frequently seen in experimental designs where the current collector plates are borrowed from fuel cell designs. These designs use a serpentine channel etched into a solid collector plate.

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TYPE SAND Report YEAR 2014
DOIOSTI

Developing highly scalable fluid solvers for enabling multiphysics simulation

Clausen, Jonathan C.

We performed an investigation into explicit algorithms for the simulation of incompressible flows using methods with a finite, but small amount of compressibility added. Such methods include the artificial compressibility method and the lattice-Boltzmann method. The impetus for investigating such techniques stems from the increasing use of parallel computation at all levels (processors, clusters, and graphics processing units). Explicit algorithms have the potential to leverage these resources. In our investigation, a new form of artificial compressibility was derived. This method, referred to as the Entropically Damped Artificial Compressibility (EDAC) method, demonstrated superior results to traditional artificial compressibility methods by damping the numerical acoustic waves associated with these methods. Performance nearing that of the lattice- Boltzmann technique was observed, without the requirement of recasting the problem in terms of particle distribution functions; continuum variables may be used. Several example problems were investigated using a finite-di erence and finite-element discretizations of the EDAC equations. Example problems included lid-driven cavity flow, a convecting Taylor-Green vortex, a doubly periodic shear layer, freely decaying turbulence, and flow over a square cylinder. Additionally, a scalability study was performed using in excess of one million processing cores. Explicit methods were found to have desirable scaling properties; however, some robustness and general applicability issues remained.

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TYPE SAND Report YEAR 2013
DOIOSTI

The rheology and microstructure of dense suspensions of elastic capsules

Clausen, Jonathan C.

We use a recently developed hybrid numerical technique [MacMeccan et al. (2009)] that combines a lattice-Boltzmann (LB) fluid solver with a finite element (FE) solid-phase solver to study suspensions of elastic capsules. The LB method recovers the Navier-Stokes hydrodynamics, while the linear FE method models the deformation of fluid-filled elastic capsules for moderate levels of deformation. The simulation results focus on accurately describing the suspension rheology, including the particle pressure, and relating these changes to changes in the microstructure. Simulations are performed with hundreds of particles in unbounded shear allowing an accurate description of the bulk suspension rheology and microstructure. In contrast to rigid spherical particles, elastic capsules are capable of producing normal stresses in the dilute limit. For dense suspensions, the first normal stress difference is of particular interest. The first normal stress difference, which is negative for dense rigid spherical suspensions, undergoes a sign change at moderate levels of deformation of the suspended capsules.

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TYPE Conference YEAR 2010
OSTI
Results 51–71 of 71
Results 51–71 of 71