Bulletin of the American Physical Society
65th Annual Meeting of the APS Division of Fluid Dynamics
Volume 57, Number 17
Sunday–Tuesday, November 18–20, 2012; San Diego, California
Session E21: Turbulence Simulation: Compressible/Hypersonic |
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Chair: Sharath Girimaji, Texas A&M University Room: 30B |
Sunday, November 18, 2012 4:45PM - 4:58PM |
E21.00001: Direct numerical simulation of compressible Kolmogorov flow Rebecca Bertsch, Sharath Girimaji, Gaurav Kumar Direct numerical simulations to investigate three-dimensional compressible turbulent Kolmogorov flow using the gas kinetic method are performed. The evolutions of single modes in isolation are examined in order to gain insight into the evolution of statistics of modes in collection. Single modes, or straight modes, are either stream-wise or span-wise and their combinations refer to oblique modes. Oblique modes (initially two-dimensional) are analyzed to isolate unstable modes and study the effect of gradient Mach number and Taylor-microscale Reynolds number. The competition between the Kelvin-Helmholtz and uniform shear instability is observed to determine the effect on flow-thermodynamic interactions. Simulations of turbulent Kolmogorov flow with varying amount of compressibility, determined by the gradient Mach number, are analyzed to support prior results of the stabilizing effect of compressibility in turbulent shear flows. [Preview Abstract] |
Sunday, November 18, 2012 4:58PM - 5:11PM |
E21.00002: Reynolds and Mach number scaling in compressible isotropic turbulence Shriram Jagannathan, Diego Donzis A large database of well-resolved Direct Numerical Simulations of forced compressible isotropic turbulence, including recent simulations at $2048^3$, with Taylor Reynolds numbers up to 400, and a range of Mach numbers ($M_t$) is used to investigate Reynolds and Mach number effects in compressible turbulence. The spectrum of dilatational energy is greatly affected by compressibility, unlike the solenoidal part. The density spectrum shows an incipient $k^{-5/3}$ at high Reynolds whose height increases with $M_t$. The scaling of dissipation and pressure-dilatation, the two exchange mechanisms between kinetic and internal energy, are also investigated. While the dilatational dissipation scales as $M_{t}^2$ at low Mach numbers, a stronger effect is observed at high $M_t$. Although the mean pressure-dilatation, which scales with dilatational dissipation, is small compared to the total dissipation for low Mach numbers, at high Mach numbers it is comparable to the total dissipation. The probability density function of pressure-dilatation shows fluctuations greater than O(100) times the mean indicating localized but strong positive and negative transfers which tend to give only a small net contribution when averaged over space. This effect increases at high Reynolds and low Mach numbers. [Preview Abstract] |
Sunday, November 18, 2012 5:11PM - 5:24PM |
E21.00003: Turbulence statistics with quantified uncertainty in cold-wall supersonic channel flow Rhys Ulerich, Robert D. Moser To investigate compressibility effects in wall-bounded turbulence, a series of direct numerical simulations of compressible channel flow with isothermal (cold) walls have been conducted. All combinations of $\mbox{Re}=\left\{3000, 5000\right\}$ and $\mbox{Ma}=\left\{0.1, 0.5, 1.5, 3.0\right\}$ have been simulated where the Reynolds and Mach numbers are based on bulk velocity and sound speed at the wall temperature. Turbulence statistics with precisely quantified uncertainties computed from these simulations will be presented and are being made available in a public data base at http://turbulence.ices.utexas.edu/. The simulations were performed using a new pseudo-spectral code called Suzerain, which was designed to efficiently produce high quality data on compressible, wall-bounded turbulent flows using a semi-implicit Fourier/B-spline numerical formulation. [Preview Abstract] |
Sunday, November 18, 2012 5:24PM - 5:37PM |
E21.00004: Strong shock and turbulence interactions w/ or w/o thermochemical non-equilibrium effects Xiaowen Wang, Pradeep S. Rawat, Xiaolin Zhong The underlying physics in shock and turbulence interaction is essential for a better understanding of many natural processes as well as scientific and engineering applications. One of the fundamental building blocks in these complex processes and applications is the canonical problem of isotropic turbulence and normal shock. Unfortunately, even this fundamental problem is not well understood for strong shocks. We have conducted extensive DNS studies on strong shock and turbulence interaction for perfect gas flow with mean Mach numbers ranging from 2 to 30. The results show some new trends in turbulent statistics as mean Mach number is increased. However, gas temperature increases dramatically after strong shocks so that numerical simulations based on perfect gas flow may not be enough. The effects of thermochemical non-equilibrium flow including internal energy excitations, translation-vibration energy relaxation, and chemical reactions among different species need to be considered. We have developed a new high-order shock-fitting solver based on the 5-species air chemistry and recently thermal non-equilibrium models. The code package has been tested and applied to DNS of strong shock and turbulence interactions with thermochemical non-equilibrium effects. [Preview Abstract] |
Sunday, November 18, 2012 5:37PM - 5:50PM |
E21.00005: ABSTRACT WITHDRAWN |
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