Pressure, density, temperature and entropy fluctuations in compressible turbulent plane channel flow

Gerolymos, G. A.; Vallet, I.

doi:10.1017/jfm.2014.431

Cited by 40 publications

(78 citation statements)

References 83 publications

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“…Isothermal no-slip wall conditions are applied on the lower and upper walls. In order to counteract viscous friction and maintain a target bulk mass flow, the approach described in Gerolymos, Sénéchal & Vallet (2010) and Gerolymos & Vallet (2014) is used to compute the forcing term. Specifically, at the end of each Runge-Kutta stage, the bulk density is explicitly constrained to maintain a fixed target value, whereas a source term f u 1 is injected in the streamwise momentum equation to enforce a constant mass flow.…”

Section: Numerical Experiments Of Compressible Channel Flowsmentioning

confidence: 99%

“…Wei & Pollard (2011) studied the influence of the Mach number, M = 0.2, 0.7 and 1.5, at constant bulk Reynolds number and proposed budgets of transport properties. Gerolymos & Vallet (2014) performed a series of DNS and derived transport equations to study in detail the variance of thermodynamic fluctuations. Trettel & Larsson (2016) gave a theoretical framework to the semi-local scaling of Huang et al (1995) showing that the scaling of the wall distance is important to take into account the variable mean properties.…”

Section: Introductionmentioning

confidence: 99%

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Direct numerical simulations of supersonic turbulent channel flows of dense gases

2017

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The influence of dense-gas effects on compressible wall-bounded turbulence is investigated by means of direct numerical simulations of supersonic turbulent channel flows. Results are obtained for PP11, a heavy fluorocarbon representative of dense gases, the thermophysics properties of which are described by using a fifth-order virial equation of state and advanced models for the transport properties. In the dense-gas regime, the speed of sound varies non-monotonically in small perturbations and the dependency of the transport properties on the fluid density (in addition to the temperature) is no longer negligible. A parametric study is carried out by varying the bulk Mach and Reynolds numbers, and results are compared to those obtained for a perfect gas, namely air. Dense-gas flow exhibits almost negligible friction heating effects, since the high specific heat of the fluids leads to a loose coupling between thermal and kinetic fields, even at high Mach numbers. Despite negligible temperature variations across the channel, the mean viscosity tends to decrease from the channel walls to the centreline (liquid-like behaviour), due to its complex dependency on fluid density. On the other hand, strong density fluctuations are present, but due to the non-standard sound speed variation (opposite to the mean density evolution across the channel), the amplitude is maximal close to the channel wall, i.e. in the viscous sublayer instead of the buffer layer like in perfect gases. As a consequence, these fluctuations do not alter the turbulence structure significantly, and Morkovin’s hypothesis is well respected at any Mach number considered in the study. The preceding features make high Mach wall-bounded flows of dense gases similar to incompressible flows with variable properties, despite the significant fluctuations of density and speed of sound. Indeed, the semi-local scaling of Patel et al. (Phys. Fluids, vol. 27 (9), 2015, 095101) or Trettel & Larsson (Phys. Fluids, vol. 28 (2), 2016, 026102) is shown to be well adapted to compare results from existing surveys and with the well-documented incompressible limit. Additionally, for a dense gas the isothermal channel flow is also almost adiabatic, and the Van Driest transformation also performs reasonably well. The present observations open the way to the development of suitable models for dense-gas turbulent flows.

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Section: Numerical Experiments Of Compressible Channel Flowsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Direct numerical simulations of supersonic turbulent channel flows of dense gases

2017

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“…density for the dense and the perfect gas (panels a and e) are deeply different. Previous reference results [17] have shown that for air cases,…”

Section: Supersonic Turbulent Channel Flowmentioning

confidence: 88%

“…Isothermal no-slip wall conditions are applied on the lower and upper walls. In order to counteract viscous friction and maintain the target bulk mass flow, a spatially constant body force is applied in the streamwise direction [17]. In the following, the subscripts (·) cw .…”

Section: Supersonic Turbulent Channel Flowmentioning

confidence: 99%

DNS of turbulent flows of dense gases

Sciacovelli

Cinnella

Gloerfelt

et al. 2017

J. Phys.: Conf. Ser.

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Abstract. The influence of dense gas effects on compressible turbulence is investigated by means of numerical simulations of the decay of compressible homogeneous isotropic turbulence (CHIT) and of supersonic turbulent flows through a plane channel (TCF). For both configurations, a parametric study on the Mach and Reynolds numbers is carried out. The dense gas considered in these parametric studies is PP11, a heavy fluorocarbon. The results are systematically compared to those obtained for a diatomic perfect gas (air). In our computations, the thermodynamic behaviour of the dense gases is modelled by means of the Martin-Hou equation of state. For CHIT cases, initial turbulent Mach numbers up to 1 are analyzed using mesh resolutions up to 512 3 . For TCF, bulk Mach numbers up to 3 and bulk Reynolds numbers up to 12000 are investigated. Average profiles of the thermodynamic quantities exhibit significant differences with respect to perfect-gas solutions for both of the configurations. For high-Mach CHIT, compressible structures are modified with respect to air, with weaker eddy shocklets and stronger expansions. In TCF, the velocity profiles of dense gas flows are much less sensitive to the Mach number and collapse reasonably well in the logarithmic region without any special need for compressible scalings, unlike the case of air, and the overall flow behaviour is midway between that of a variable-property liquid and that of a gas.

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“…Dense gas flows are governed by the single-phase compressible Navier-Stokes equations. For the present channel flow calculations, a source term f u i is added to the streamwise momentum equation to counteract wall friction and maintain a target bulk mass flow [21]. A corresponding term is introduced in the energy equation.…”

Section: Governing Equations and Numerical Methodsmentioning

confidence: 99%

A Priori Tests of RANS Models for Turbulent Channel Flows of a Dense Gas

Sciacovelli

Cinnella

Gloerfelt

2018

Flow Turbulence Combust

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Dense gas effects, encountered in many engineering applications, lead to unconventional variations of the thermodynamic and transport properties in the supersonic flow regime, which in turn are responsible for considerable modifications of turbulent flow behavior with respect to perfect gases. The most striking differences for wall-bounded turbulence are the decoupling of dynamic and thermal effects for gases with high specific heats, the liquid-like behavior of the viscosity and thermal conductivity, which tend to decrease away from the wall, and the increase of density fluctuations in the near wall region. The present work represents a first attempt of quantifying the influence of such dense gas effects on modeling assumptions employed for the closure of the Reynolds-averaged Navier-Stokes equations, with focus on the eddy viscosity and turbulent Prandtl number models. For that purpose, we use recent direct numerical simulation results for supersonic turbulent channel flows of PP11 (a heavy fluorocarbon representative of dense gases) at various bulk Mach and Reynolds numbers to carry out a priori tests of the validity of some currently-used models for the turbulent stresses and heat flux. More specifically, we examine the behavior of the modeled eddy viscosity for some low-Reynolds variants of the k − ε model and compare the results with those found for a perfect gas at similar conditions. We also investigate the behavior of the turbulent Prandtl number in dense gas flow and compare the results with the predictions of two well-established turbulent Prandtl number models.

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Pressure, density, temperature and entropy fluctuations in compressible turbulent plane channel flow

Cited by 40 publications

References 83 publications

Direct numerical simulations of supersonic turbulent channel flows of dense gases

Direct numerical simulations of supersonic turbulent channel flows of dense gases

DNS of turbulent flows of dense gases

A Priori Tests of RANS Models for Turbulent Channel Flows of a Dense Gas

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