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In probability density function (PDF) methods of turbulent flows, the joint PDF of several flow variables is computed by numerically integrating a system of stochastic differential equations for Lagrangian particles. A mathematically exact…

Fluid Dynamics · Physics 2010-06-17 J. Bakosi

Kinetic energy stored in ISM bulk/turbulent motions is a crucial ingredient to properly describe most properties of observed galaxies. By using Monte Carlo simulations, we investigate how this energy is injected by supernovae and dissipated…

Astrophysics · Physics 2009-11-07 Massimo Ricotti , Andrea Ferrara

Supersonic combustion plays a vital role in various applications, including scramjets, dual-mode ramjets, and pulse detonation engines. However, the flame characteristics can vary significantly, depending on the application. To model…

Fluid Dynamics · Physics 2023-06-21 Xu Zhu , Jian An , Nana Wang , Jian Zhang , Zhuyin Ren

The PDFs for energy dissipation rates created in a high resolution from $4096^3$ DNS for fully developed turbulence are analyzed in a high precision with the PDF derived within the formula of multifractal probability density function theory…

Statistical Mechanics · Physics 2015-03-19 Toshihico Arimitsu , Naoko Arimitsu , Kohei Takechi , Yukio Kaneda , Takashi Ishihara

An extension to the classical FPV model is developed for transcritical real-fluid combustion simulations in the context of finite volume, fully compressible, explicit solvers. A double-flux model is developed for transcritical flows to…

Fluid Dynamics · Physics 2017-04-11 Peter C. Ma , Daniel T. Banuti , Jean-Pierre Hickey , Matthias Ihme

Probability density function (PDF) based turbulent combustion modelling is limited by the need to store multi-dimensional PDF tables that can take up large amounts of memory. A significant saving in storage can be achieved by using various…

Computational Engineering, Finance, and Science · Computer Science 2020-05-21 Rishikesh Ranade , Genong Li , Shaoping Li , Tarek Echekki

Turbulence is a complex phenomenon that plays a critical role in the interstellar medium (ISM). Previous simulations and observations show that the probability density function (PDF) of gas density in isothermal and compressible systems…

Astrophysics of Galaxies · Physics 2025-03-26 Xunchuan Liu

Diffusive transport of mass occurs at small scales in turbulent premixed flames. As a result, multicomponent mass diffusion, which is often neglected in direct numerical simulations (DNS) of premixed combustion, has the potential to impact…

Fluid Dynamics · Physics 2022-07-20 Aaron J. Fillo , Peter E. Hamlington , Kyle E. Niemeyer

In the present paper, the flames imitating Moderate and Intense Low Oxygen Dilution (MILD) combustion are studied using the Probability Density Function (PDF) modeling approach. Two burners which imitate MILD combustion are considered for…

Fluid Dynamics · Physics 2021-02-23 Akshay Dongre , Ashoke De , Rakesh Yadav

Turbulence is essential for understanding the structure and dynamics of molecular clouds and star-forming regions. There is a need for adequate tools to describe and characterize the properties of turbulent flows. One-point probability…

Astrophysics · Physics 2008-11-26 Ralf S. Klessen

In this work, we demonstrate a framework for developing closure models in turbulent combustion using experimental multi-scalar measurements. The framework is based on the construction of conditional means and joint scalar PDFs from…

Fluid Dynamics · Physics 2019-09-10 Rishikesh Ranade , Tarek Echekki

A novel methodology to analyze non-Gaussian probability distribution functions (PDFs) of intermittent turbulent transport in global full-f gyrokinetic simulations is presented. In this work, the Auto-Regressive Integrated Moving Average…

Plasma Physics · Physics 2017-06-13 J. Anderson , K. Imadera , Y. Kishimoto , J. Q. Li , H. Nordman

A new premixed turbulent combustion model is proposed. It is based on one-dimensional (1D) filtering of density times progress variable and of the reaction source term of laminar premixed flame profiles using a filter kernel which reflects…

Fluid Dynamics · Physics 2021-12-21 Michael Pfitzner , Junsu Shin , Markus Klein

The present paper reports on the assessment of different turbulence-chemistry interaction closures for modeling turbulent combustion in the Moderate and Intense Low oxygen Dilution combustion regime. 2D RANS simulations have been carried…

Fluid Dynamics · Physics 2021-01-25 Ashoke De , Akshay Dongre

We propose a new, physically motivated fitting function for density PDFs in turbulent gas. Although it is known that when gas is isothermal, the PDF is approximately lognormal in the core, high-resolution simulations show large deviations…

Astrophysics of Galaxies · Physics 2013-07-02 Philip F. Hopkins

Two-way coupled DNS simulation of particle-laden turbulent Couette-flow [1], in the volume fraction regime $\phi>10^{-4}$, showed a discontinuous decrease of turbulence intensity beyond a critical volume fraction…

Fluid Dynamics · Physics 2022-04-04 Swagnik Ghosh , Partha Sarathi Goswami

This Letter provides a theoretical interpretation of numerically generated probability density functions (PDFs) of intermittent plasma transport events. Specifically, nonlinear gyrokinetic simulations of ion-temperature-gradient turbulence…

Plasma Physics · Physics 2010-11-10 Johan Anderson , Pavlos Xanthopoulos

A purely data-driven approach using deep convolutional neural networks is discussed in the context of Large Eddy Simulation (LES) of turbulent premixed flames. The assessment of the method is conducted a priori using direct numerical…

Fluid Dynamics · Physics 2018-10-22 Zacharias M. Nikolaou , Charalambos Chrysostomou , Luc Vervisch , Stewart Cant

We study density fluctuations in supersonic turbulence using both theoretical methods and numerical simulations. A theoretical formulation is developed for the probability distribution function (PDF) of the density at steady state,…

Astrophysics of Galaxies · Physics 2019-09-04 Liubin Pan , Paolo Padoan , Åke Nordlund

Mixture fraction-based models are widely employed for predicting turbulent non-premixed combustion processes due to their cost-effectiveness and well-established subfilter closure. In these models, the transport of reactive scalars in…

Fluid Dynamics · Physics 2023-10-26 Marco Davidovic , Heinz Pitsch