DNS of a Periodic Channel Flow with Isothermal Ablative Wall

Cabrit, Olivier; Nicoud, Franck

doi:10.1007/978-90-481-3652-0_5

Cited by 3 publications

(2 citation statements)

References 13 publications

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“…The solution adopted has 5 layers of prisms where the vertical length of the prism Dy is smaller than the triangle base-length Dx or Dz (here, D x $ Dz) resulting in a minimum cell volume that is increased if compared to a full tetrahedral option. A limit is imposed to this mesh adaptation to avoid numerical errors in these layers, the aspect ratio of the first and thinnest layer is set to Dx + $ 4Dy + , i.e., x + %4y + in agreement with known observations and boundary layer scales [11]. The last constraint to control, which is known to be critical numerically, is the stretching ratio.…”

Section: Computational Domain and Mesh Generationmentioning

confidence: 99%

Effects of free-stream turbulence on high pressure turbine blade heat transfer predicted by structured and unstructured LES

Morata¹,

Gourdain

Duchaine

et al. 2012

International Journal of Heat and Mass Transfer

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a b s t r a c tRecent developments and demonstrations for the prediction of turbulent flows around blades point to Large Eddy Simulations (LES) as a very promising tool. Indeed and despite the fact that this numerical method still requires modeling and intense computing effort compared to Reynolds Average NavierStokes (RANS), this fully unsteady simulation technique provides valuable information on the turbulent flow otherwise inaccessible. Theoretical limits and scales of wall bounded flows are now well mastered in simple cases but complex industrial applications usually introduce unknowns and mechanisms that are difficult to apprehend beforehand especially with LES which is usually computationally intensive and bounded to code scalability, mesh quality, modeling performances and computer power. In this specific context, few studies directly address the use of fully structured versus unstructured, implicit versus explicit flow solvers and their respective impact for LES modeling of complex wall bounded flows. To partly address these important issues, two dedicated structured and unstructured computational solvers are applied and assessed by comparing the predictions of the heat transfer around the experimental high pressure turbine blade profile cascade of Arts et al. [6]. First, both LES predictions are compared to RANS modeling with a particular interest for the accuracy/cost ratio and improvement of the physical phenomena around the blade. LES's are then detailed and further investigated to assess their ability to reproduce the inlet turbulence effect on heat transfer and the development of the transitioning boundary layer around the blade. Quantitative comparisons against experimental findings show excellent agreement especially on the pressure side of the profile. Detailed analysis of the flow predictions provided by both the structured and unstructured solvers underline the importance of long stream-wise streaky structures responsible for the augmentation of the heat transfer and leading to the transition of the suction-side boundary layer.

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Section: Computational Domain and Mesh Generationmentioning

confidence: 99%

Effects of free-stream turbulence on high pressure turbine blade heat transfer predicted by structured and unstructured LES

Morata¹,

Gourdain

Duchaine

et al. 2012

International Journal of Heat and Mass Transfer

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“…In 1987, Kim et al 8 were among the first authors to provide reliable turbulence statistics in fully developed channel flows. A large number of studies dealing with isothermal turbulent flows at mean Reynolds numbers inferior or equal to 395 have been carried out since then [9][10][11] . Direct numerical simulations of highly turbulent channel flow are more recent [12][13][14][15][16] .…”

Section: Introductionmentioning

confidence: 99%

Direct simulations and subgrid modeling of turbulent channel flows asymmetrically heated from both walls

2021

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Thermal Large-Eddy Simulations (T-LES) and a Direct Numerical Simulation (DNS) are carried out in a bi-periodical channel with hot and cold wall temperatures of respectively 900 K and 1300 K. The mean fluid temperature is lowered below the cold wall temperature thanks to a heat source, resulting in a both walls heating of the fluid. The hot and cold wall friction Reynolds numbers are respectively 640 and 1000. These conditions are representative of the working conditions of gas-pressurized solar receiver of solar power tower. The Low Mach number Navier-Stokes equations are solved. The coupling between the dynamic and the temperature effects is considered. In the T-LES, both the momentum convection and the density-velocity correlation subgrid terms are modeled. Functional models, structural models, and mixed models are considered. A tensorial version of the Anisotropic Minimum-Dissipation (AMD) model is also investigated. The Quick and the second-order centered schemes are tested for the discretization of the mass convection term. Firstly, an overview of the results of 17 T-LES on first-and second-order statistics is proposed. It permits selecting 6 of these simulations for a detailed analysis consisting in the investigation of profiles of mean quantities and turbulent correlations. A particular attention is given to the wall heat fluxes because it is a critical point for the design and the optimization of solar receivers. Overall, the first-order statistics are better predicted than the second-order's. The tensorial AMD model takes advantage of the classical AMD model properties and better reproduces the anisotropy of the flow thanks to its formulation. The tensorial AMD model produces the most reliable and efficient results among the considered models.

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Analysis of Wall Thermochemical Ablation by the Use of Direct Simulations of Turbulent Periodic Channel Flow

Cabrit

Nicoud

2009

Proceeding of Sixth International Symposium on Turbulence and Shear Flow Phenomena

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DNS of a Periodic Channel Flow with Isothermal Ablative Wall

Cited by 3 publications

References 13 publications

Effects of free-stream turbulence on high pressure turbine blade heat transfer predicted by structured and unstructured LES

Effects of free-stream turbulence on high pressure turbine blade heat transfer predicted by structured and unstructured LES

Direct simulations and subgrid modeling of turbulent channel flows asymmetrically heated from both walls

Analysis of Wall Thermochemical Ablation by the Use of Direct Simulations of Turbulent Periodic Channel Flow

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