Investigation of high-pressure turbulent jets using direct numerical simulation

Sharan, Nek; Bellan, Josette

doi:10.1017/jfm.2021.524

Cited by 10 publications

(4 citation statements)

References 71 publications

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“…In this case, friction heating causes large density perturbations as a result of the transition between liquid-like and gas-like states within the boundary layer due to the thermodynamic states crossing of the Widom line. Destabilization of laminar jet flows of fluids in transcritical thermodynamic states as a result of the larger velocity fluctuations has also been observed by Sharan & Bellan (2021).…”

Section: Instabilities In Wall-shear and Free-shear Laminar Flowsmentioning

confidence: 68%

Nonideal Compressible Fluid Dynamics of Dense Vapors and Supercritical Fluids

Guardone,

Colonna,

Pini

et al. 2024

Annu. Rev. Fluid Mech.

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The gas dynamics of single-phase nonreacting fluids whose thermodynamic states are close to vapor-liquid saturation, close to the vapor-liquid critical point, or in supercritical conditions differs quantitatively and qualitatively from the textbook gas dynamics of dilute, ideal gases. Due to nonideal fluid thermodynamic properties, unconventional gas dynamic effects are possible, including nonclassical rarefaction shock waves and the nonmonotonic variation of the Mach number along steady isentropic expansions. This review provides a comprehensive theoretical framework of the fundamentals of nonideal compressible fluid dynamics (NICFD). The relation between nonideal gas dynamics and the complexity of the fluid molecules is clarified. The theoretical, numerical, and experimental tools currently employed to investigate NICFD flows and related applications are reviewed, followed by an overview of industrial processes involving NICFD, ranging from organic Rankine and supercritical CO2 cycle power systems to supercritical processes. The future challenges facing researchers in the field are briefly outlined.

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Section: Instabilities In Wall-shear and Free-shear Laminar Flowsmentioning

confidence: 68%

Nonideal Compressible Fluid Dynamics of Dense Vapors and Supercritical Fluids

Guardone,

Colonna,

Pini

et al. 2024

Annu. Rev. Fluid Mech.

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“…The jet flow field is represented as a scalar-field that has a value of 1.0 for pure fluid originating from the nozzle and 0.0 for the surrounding fluid, with values between 0 and 1 indicating the mixture between the jet and the surrounding fluid. The jet originates from a circular nozzle with an exit diameter of 2.36 mm with a Reynolds number of 5000 as described by Sharan and Bellan [29]. The data is analogous to several flow diagnostic techniques, including LIF in combustion, or passive scalar flow visualizations such as that achieved with dye or smoke injection.…”

Section: Synthetic Data Setmentioning

confidence: 99%

Investigation of a neural implicit representation tomography method for flow diagnostics

Kelly,

Thurow

2024

Meas. Sci. Technol.

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In this work, a new gridless approach to tomographic reconstruction of 3D flow fields is introduced and investigated. The approach, termed here as FluidNeRF, is based on the concept of volume representation through Neural Radiance Fields (NeRF). NeRF represents a 3D volume as a continuous function using a deep neural network. In FluidNeRF, the neural network is a function of 3D spatial coordinates in the volume and produces an intensity of light per unit volume at that position. The network is trained using the loss between measured and rendered 2D projections similar to other multi-camera tomography techniques. Projections are rendered using an emission-based integrated line-of-sight method where light rays are traced through the volume; the network is used to determine intensity values along the ray. This paper investigates the influence of the NeRF hyperparameters, camera layout and spacing, and image noise on the reconstruction quality as well as the computational cost. A DNS-generated synthetic turbulent jet is used as a ground-truth representative flow field. Results obtained with FluidNeRF are compared to an adaptive simultaneous algebraic reconstruction technique (ASART), which is representative of a conventional reconstruction technique. Results show that FluidNeRF matches or outperforms ASART in reconstruction quality, is more robust to noise, and offers several advantages that make it more flexible and thus suitable for extension to other flow measurement techniques and scaling to larger-scale problems.

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“…A great deal of attention has recently been directed to understanding how the properties of these fluids affect turbulence, in particular turbulent heat transfer (Yoo 2013). Recent studies have investigated the statistics of turbulence in different shear flows by means of DNS, for example in channel (Nemati et al 2015;Patel, Boersma & Pecnik 2016;Sciacovelli, Cinnella & Gloerfelt 2017), pipe (Peeters et al 2016;He et al 2021), jet (Sharan & Bellan 2021) or flat-plate boundary layer flows (Kawai 2019;Sciacovelli et al 2020). However, little is known about stability and transition to turbulence in these fluids (Robinet & Gloerfelt 2019).…”

Section: Recent Developments In the Hydrodynamics Of Supercritical Fl...mentioning

confidence: 99%

“…2016; He et al. 2021), jet (Sharan & Bellan 2021) or flat-plate boundary layer flows (Kawai 2019; Sciacovelli et al. 2020).…”

Section: Introductionmentioning

confidence: 99%

Instability in strongly stratified plane Couette flow with application to supercritical fluids

Bugeat,

Boldini,

Hasan

et al. 2024

J. Fluid Mech.

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This paper addresses the stability of plane Couette flow in the presence of strong density and viscosity stratifications. It demonstrates the existence of a generalised inflection point that satisfies the generalised Fjørtoft criterion of instability when a minimum of kinematic viscosity is present in the base flow. The characteristic scales associated with this minimum are identified as the primary controlling parameters of the associated instability, regardless of the type of stratification. To support this finding, analytical stability models are derived in the long-wave approximation using piecewise linear base flows. Numerical stability calculations are carried out to validate these models and to provide further information on the production of disturbance vorticity. All instabilities are interpreted as arising from the interaction between two vorticity waves. Depending on the type of stratification, these two waves are produced by different physical mechanisms. When both strong density and viscosity stratifications are present, we show that they result from the concurrent action of shear and inertial baroclinic effects. The stability models developed for simple fluid models ultimately shed light on a recently observed unstable mode in supercritical fluids (Ren et al., J. Fluid Mech., vol. 871, 2019, pp. 831–864), providing a quantitative prediction of the stability diagram and identifying the dominant mechanisms at play. Furthermore, our study suggests that the minimum of kinematic viscosity reached at the Widom line in these fluids is the leading cause of their instability. The existence of similar instabilities in different fluids and flows (e.g. miscible fluids) is finally discussed.

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Investigation of high-pressure turbulent jets using direct numerical simulation

Abstract: Abstract

Cited by 10 publications

References 71 publications

Nonideal Compressible Fluid Dynamics of Dense Vapors and Supercritical Fluids

Nonideal Compressible Fluid Dynamics of Dense Vapors and Supercritical Fluids

Investigation of a neural implicit representation tomography method for flow diagnostics

Instability in strongly stratified plane Couette flow with application to supercritical fluids

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