Towards direct numerical simulations of low-Mach number turbulent reacting and two-phase flows using immersed boundaries

Abdelsamie, Abouelmagd; Fru, Gordon; Oster, Timo; Dietzsch, Felix; Janiga, Gábor; Thévenin, Dominique

doi:10.1016/j.compfluid.2016.03.017

Cited by 85 publications

(26 citation statements)

References 57 publications

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“…As the computing power advances, DNS has become feasible for systematic study on ignition processes in 2D, providing accurate information on fluid dynamics and chemical composition. In the present study, the parallel DNS flame solver DINO [32] is used. It solves the low-Mach Navier-Stokes system coupled with detailed physicochemical models.…”

Section: Problem Configuration and Initializationmentioning

confidence: 99%

Direct Numerical Simulations of Hotspot-induced Ignition in Homogeneous Hydrogen-air Pre-mixtures and Ignition Spot Tracking

Chi

Abdelsamie

Thévenin

2018

Flow Turbulence Combust

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A systematic study relying on Direct Numerical Simulations (DNS) of premixed hydrogen-air mixtures has been performed to investigate the hotspot ignition characteristics and ignition probability under turbulent conditions. An ignition diagram is first obtained under laminar conditions by a parametric study. The impact of turbulence intensity on ignition delays and ignition probability is then quantified in a statistically-significant manner by repeating a large number of independent DNS realizations. By tracking in a Lagrangian frame the ignition spot, the balance between heat diffusion and heat of chemical reaction is observed as function of time. The evolution of each chemical species and radicals at the ignition spot is checked and the mechanism leading to ignition or misfire are analyzed. It is observed that successful ignition is mostly connected to a sufficient build-up of a HO2 pool, ultimately initiating production of OH. Turbulence always delays ignition, and ignition probability goes to zero at sufficiently high turbulence intensity when keeping temperature and size of the initial hotspot constant.

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Section: Problem Configuration and Initializationmentioning

confidence: 99%

Direct Numerical Simulations of Hotspot-induced Ignition in Homogeneous Hydrogen-air Pre-mixtures and Ignition Spot Tracking

Chi

Abdelsamie

Thévenin

2018

Flow Turbulence Combust

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“…Our algorithm is implemented as an extension to the DINO DNS code [AFO*16]. The simulation domain is a rectangular box which is distributed to multiple processors by a block decomposition along two of its three axes.…”

Section: Methodsmentioning

confidence: 99%

On‐The‐Fly Tracking of Flame Surfaces for the Visual Analysis of Combustion Processes

Oster

Abdelsamie

Motejat

et al. 2018

Computer Graphics Forum

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The visual analysis of combustion processes is one of the challenges of modern flow visualization. In turbulent combustion research, the behaviour of the flame surface contains important information about the interactions between turbulence and chemistry. The extraction and tracking of this surface is crucial for understanding combustion processes. This is impossible to realize as a post‐process because of the size of the involved datasets, which are too large to be stored on disk. We present an on‐the‐fly method for tracking the flame surface directly during simulation and computing the local tangential surface deformation for arbitrary time intervals. In a massively parallel simulation, the data are distributed over many processes and only a single time step is in memory at any time. To satisfy the demands on parallelism and accuracy posed by this situation, we track the surface with independent micro‐patches and adapt their distribution as needed to maintain numerical stability. With our method, we enable combustion researchers to observe the detailed movement and deformation of the flame surface over extended periods of time and thus gain novel insights into the mechanisms of turbulence–chemistry interactions. We validate our method on analytic ground truth data and show its applicability on two real‐world simulations.

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“…Fine scale variations of both kinematic and dynamic viscosity coefficients as well as of diffusion coefficients are neglected as it is common in numerical methods for turbulent flows with mixing, buoyancy or combustion. The same assumption applies also for the pressure fluctuations [8]. Substitution of the decomposition (12) in the (10) gives…”

Section: Decomposition Of Vorticity and Continuity Equations Accordinmentioning

confidence: 95%

“…which is solved using the OpenFOAM. The motion of fine vortices is governed by the Equations 7and (8). Once at any time instant, the grid solution step is completed, the evolution of fine vortices is carried out in the following sequence: generation, motion, feedback effect on large scales through the term u v × ω g , mapping to the grid or elimination.…”

Section: Vπles For Incompressible Flowsmentioning

confidence: 99%

Theoretical Background of the Hybrid VπLES Method for Flows with Variable Transport Properties

Kornev

Denev

Samarbakhsh

2020

Fluids

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The paper presents the theoretical basis for the extension of the V π LES method, originally developed in recent works of the authors for incompressible flows, to flows with variable density and transport properties but without chemical reactions. The method is based on the combination of grid based and grid free computational particle techniques. Large scale motions are modelled on the grid whereas the fine scale ones are modelled by particles. The particles represent the fine scale vorticity, and scalar quantities like e.g., temperature, mass fractions of species, density and mixture fraction. Coupled system of equations is derived for large and fine scales transport.

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Towards direct numerical simulations of low-Mach number turbulent reacting and two-phase flows using immersed boundaries

Cited by 85 publications

References 57 publications

Direct Numerical Simulations of Hotspot-induced Ignition in Homogeneous Hydrogen-air Pre-mixtures and Ignition Spot Tracking

Direct Numerical Simulations of Hotspot-induced Ignition in Homogeneous Hydrogen-air Pre-mixtures and Ignition Spot Tracking

On‐The‐Fly Tracking of Flame Surfaces for the Visual Analysis of Combustion Processes

Theoretical Background of the Hybrid VπLES Method for Flows with Variable Transport Properties

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