Bulletin of the American Physical Society
66th Annual Meeting of the APS Division of Fluid Dynamics
Volume 58, Number 18
Sunday–Tuesday, November 24–26, 2013; Pittsburgh, Pennsylvania
Session M26: Reacting Flows VIII: General |
Hide Abstracts |
Chair: Carlos Pantano, University of Illinois at Urbana-Champaign Room: 321 |
Tuesday, November 26, 2013 8:00AM - 8:13AM |
M26.00001: Direct numerical simulation of turbulent autoigniting flames Rajapandiyan Asaithambi, Krishnan Mahesh A density based method for DNS/LES of compressible chemically reacting flows is proposed with an explicit predictor step for advection and diffusion terms, and a semi-implicit corrector step for stiff chemical source terms. This segregated approach permits independent modification of the Navier-Stokes solver and the time integration algorithm for the chemical source term. The numerical details are briefly summarized and results from autoigniting non-premixed flames in vitiated coflow with different fuels are discussed. We perform a direct numerical simulation of a turbulent round hydrogen jet at a Reynolds number of $\sim$12,500 injected into coflowing hot air. Flow statistics and the physics of the flame ignition and stabilization will be discussed. [Preview Abstract] |
Tuesday, November 26, 2013 8:13AM - 8:26AM |
M26.00002: Solution of variable-density edge flames by a homotopy method Kai-Pin Liao, Moshe Matalon, Carlos Pantano The edge flame is a fundamental flame structure essential to the description of flame hole dynamics in turbulent nonpremixed combustion and the stabilization of lifted jet flames. The edge flame propagation velocity is a solution to a nonlinear eigenvalue problem based on the variable-density reactive Navier-Stokes equations. This problem is remarkably difficult to solve as a boundary-value problem due to the two-dimensionality of edge flames and the nonlinear nature of the equations. In this talk we present a novel algorithm to solve for the steady state solution of the system using a homotopy method that maps continuously the easy-to-find constant-density solution into the variable-density flow. The flow and the combustion fields are segregated within an outer Picard iteration embedding a Newton method, which is solved sequentially using GMRES with proper multigrid preconditioners. This efficient algorithm enables the parametric study of the effects of thermal expansion, differential diffusion, heat release, and strain rate on edge flame structure and propagation velocity for variable-density flows. Furthermore, a discussion of admissible boundary conditions for this problem will be presented. [Preview Abstract] |
Tuesday, November 26, 2013 8:26AM - 8:39AM |
M26.00003: Log-Normality and Multifractal Analysis of Flame Surface Statistics Abhishek Saha, Swetaprovo Chaudhuri, Chung K. Law The turbulent flame surface is typically highly wrinkled and folded at a multitude of scales controlled by various flame properties. It is useful if the information contained in this complex geometry can be projected onto a simpler regular geometry for the use of spectral, wavelet or multifractal analyses. Here we investigate local flame surface statistics of turbulent flame expanding under constant pressure. First the statistics of local length ratio is experimentally obtained from high-speed Mie scattering images. For spherically expanding flame, length ratio on the measurement plane, at predefined equiangular sectors is defined as the ratio of the actual flame length to the length of a circular-arc of radius equal to the average radius of the flame. Assuming isotropic distribution of such flame segments we convolute suitable forms of the length-ratio probability distribution functions (\textit{pdf}s) to arrive at corresponding area-ratio \textit{pdf}s. Both the \textit{pdf}s are found to be near log-normally distributed and shows self-similar behavior with increasing radius. Near log-normality and rather intermittent behavior of the flame-length ratio suggests similarity with dissipation rate quantities which stimulates multifractal analysis. [Preview Abstract] |
Tuesday, November 26, 2013 8:39AM - 8:52AM |
M26.00004: Reactive transport modeling of CO$_{2}$ inside a fractured rock: Implications of mass transfer and storage capacity Mohammad Alizadeh Nomeli, Amir Riaz A numerical model of geochemical transport is developed to evaluate long term mineral trapping of CO$_{2}$ inside a fractured rock. The problem contains flow of CO$_{2}$ between finite plates that represents a single fracture in post-injection regime. This study investigates the impact of fractures on CO$_{2}$ transport and storage capacity. The effect of surface roughness is also investigated to predict the actual efficiency of mineral trapping of CO$_{2}$ for a long period of time. The model is composed of direct numerical simulation tools and algorithms for incompressible flow and conservative transport combined with kinetics of corresponding chemical reactions. For each time step, transport and reactions are solved by means of finite difference method using a sequential non-iterative approach. It is found that the simple fracture is filled at the inlet because concentrations of carbonate ions are greater (more saturated states). [Preview Abstract] |
Tuesday, November 26, 2013 8:52AM - 9:05AM |
M26.00005: Rayleigh-Taylor Unstable Flames -- Fast or Faster? Elizabeth Hicks The speed of a Rayleigh-Taylor unstable, premixed flame could plausibly be influenced by both the Rayleigh-Taylor instability of the flame front and the turbulence generated by the flame itself. Both of these mechanisms stretch and wrinkle the flame front, increasing its surface area and speed. But which of these two processes is dominant? Is the flame speed better modeled by the Rayleigh-Taylor speed or the root-mean-square velocity of the turbulence? To address these questions, we will present the results from three-dimensional, direct numerical simulations of Rayleigh-Taylor unstable flames that generate moderately turbulent conditions. We will discuss the influence of the Rayleigh-Taylor instability and turbulence on the flame front and focus on cases for which the flame speed substantially exceeds the laminar flame speed. [Preview Abstract] |
Tuesday, November 26, 2013 9:05AM - 9:18AM |
M26.00006: Thermal convection and gyrokinetic effects in inductively-coupled plasma-based lenses Milad Mortazavi, Javier Urzay, Ali Mani The principle of operation of a plasma lens consists of tuning the electron-density field, or equivalently, the refractive-index distribution in an ionized gas environment. The use of larger and more powerful lenses with higher electron-density results in higher optical performance and resolution, but also leads to hydrodynamic instabilities and noticeable bulk motion in the plasma, which may be detrimental for its optical performance. In this investigation, the effects of thermal convection and mean gyrokinetic motion are analyzed on an inductively-coupled Argon-plasma lens. The analyses utilize theoretical and computational methods to identify relevant characteristic parameters and operating regimes of interest for the optimal use of the plasma lens. [Preview Abstract] |
Tuesday, November 26, 2013 9:18AM - 9:31AM |
M26.00007: A constitutive theory of reacting electrolyte mixtures Martina Costa Reis, Yongqi Wang, Adalberto Bono Maurizio Sacchi Bassi A constitutive theory of reacting electrolyte mixtures is formulated. The intermolecular interactions among the constituents of the mixture are accounted for through additional freedom degrees to each constituent of the mixture. Balance equations for polar reacting continuum mixtures are accordingly formulated and a proper set of constitutive equations is derived with basis in the M\"{u}ller-Liu formulation of the second law of thermodynamics. Moreover, the non-equilibrium and equilibrium responses of the reacting mixture are investigated in detail by emphasizing the inner and reactive structures of the medium. From the balance laws and constitutive relations, the effects of molecular structure of constituents upon the fluid flow are studied. It is also demonstrated that the local thermodynamic equilibrium state can be reached without imposing that the set of independent constitutive variables is time independent, neither spatially homogeneous nor null. The resulting constitutive relations presented throughout this work are of relevance to many practical applications, such as swelling of clays, developing of bio and polymeric membranes, and use of electrorheological fluids in industrial processes. [Preview Abstract] |
Tuesday, November 26, 2013 9:31AM - 9:44AM |
M26.00008: Laminar Flame Speed of Primary Reference Fuels and Gasoline Surrogates at Elevated Temperatures Measured with the Flat Flame Method Ying-Hao Liao, William Roberts The laminar flame speed is a key target data for validating relevant kinetic mechanisms of the combustion of future fuel formulations since this fundamental parameter contains information for the reactivity, diffusivity, and exothermicity of the fuel mixture. The current work presents the flat flame method, which produces a one-dimensional flat flame free of stretch, to measure laminar flame speeds of the Primary Reference Fuels (PRFs), PRF blends, and gasoline surrogates at elevated temperatures. The flat flame is produced by a McKenna porous plug burner. The laminar flame speed was measured experimentally at atmospheric pressure over a range of equivalence ratios and a range of unburned gas temperatures up to 470 K. To determine the laminar flame speed, a technique with heat extraction through the cooling water, similar to that described by Botha and Spalding (1954), was employed and the adiabatic laminar flame speed was obtained by extrapolation. In addition, the experimental data is compared to simulations using kinetic mechanisms available in the literature. Preliminary results of laminar flame speeds for methane/air and n-heptane/air mixtures at room temperature show good agreement with both of experimental and numerical data available in the literature. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2022 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
1 Research Road, Ridge, NY 11961-2701
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700