Effect of thermo-mechanical non-equilibrium on the onset of transition in supersonic boundary layers

Sharma, Sushank; Shadloo, Mostafa Safdari; Hadjadj, A.

doi:10.1007/s00231-018-2429-9

Cited by 9 publications

(3 citation statements)

References 22 publications

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“…Furthermore, the temperature gradient near the wall increases with the decreasing of cooling temperature. The temperature gradient near the wall means thermomechanical non-equilibrium, which will lead to the transition onset occurring more upstream than the thermomechanical equilibrium wall in a Mach 2.2 boundary layer (Sharma, Shadloo & Hadjadj 2019 a ). This is the reason that the growth rate of mode (1,1) for case is greater than that of cases and at the third stage (see figure 17 a ).…”

Section: Resultsmentioning

confidence: 99%

Control of oblique breakdown in a supersonic boundary layer employing a local cooling strip

Zhou

Liu

et al. 2022

J. Fluid Mech.

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Oblique breakdown in a Mach 2.0 supersonic boundary layer controlled by a local cooling strip with a temperature jump is investigated using direct numerical simulations and linear stability theory. The effect of temperature on the stability of the fundamental oblique waves is first studied by linear stability theory. It is shown that the growth rate of fundamental oblique waves will decrease monotonically as the temperature decreases. However, the results of the direct numerical simulations indicate that transition reversal will occur as the growth rate of the fundamental oblique waves of cooled case becomes faster compared with that of baseline case downstream of the cooling strip. When the cooling strip is in the linear region, the transition is delayed due to the suppression effect of the cooling strip on the fundamental oblique waves. When the cooling strip is located in the early nonlinear region, the fundamental oblique waves will be suppressed by higher spanwise wavenumber steady modes generated by the mutual and self-interaction between the fundamental oblique waves and harmonic modes, which is first called the self-suppression effect (SSE) in the present study. Further research indicated that the meanflow distortion generated by steady modes plays an important role in the SSE. Compared with the stabilization effect of the cooling strip, the SSE is more effective. Moreover, the SSE might provide a new idea on the instability control, as it is observed that the SSE works three times leading to the growth rate of fundamental oblique waves slowing down at three different regions, respectively.

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Section: Resultsmentioning

confidence: 99%

Control of oblique breakdown in a supersonic boundary layer employing a local cooling strip

Zhou

Liu

et al. 2022

J. Fluid Mech.

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“…The main idea of these methods is to identify the coherent modes that dominate in the measured signal. The DMD can be efficiently used when it is necessary to reveal frequency information and corresponding spatial structures throughout the field [ 58 , 59 , 60 ]. So, the DMD seems to be preferable for a detailed investigation of the flow structure.…”

Section: Proper Orthogonal Decompositionmentioning

confidence: 99%

On the Scope of Lagrangian Vortex Methods for Two-Dimensional Flow Simulations and the POD Technique Application for Data Storing and Analyzing

Kuzmina

Marchevsky

Soldatova

et al. 2021

Entropy

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The possibilities of applying the pure Lagrangian vortex methods of computational fluid dynamics to viscous incompressible flow simulations are considered in relation to various problem formulations. The modification of vortex methods—the Viscous Vortex Domain method—is used which is implemented in the VM2D code developed by the authors. Problems of flow simulation around airfoils with different shapes at various Reynolds numbers are considered: the Blasius problem, the flow around circular cylinders at different Reynolds numbers, the flow around a wing airfoil at the Reynolds numbers 104 and 105, the flow around two closely spaced circular cylinders and the flow around rectangular airfoils with a different chord to the thickness ratio. In addition, the problem of the internal flow modeling in the channel with a backward-facing step is considered. To store the results of the calculations, the POD technique is used, which, in addition, allows one to investigate the structure of the flow and obtain some additional information about the properties of flow regimes.

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“…The residuals of all equations were set equal to 10 −7 . The details of the governing equations can be found at (Shadloo et al , 2016a; Hopp-Hirschler et al , 2018; Sharma et al , 2018; Méndez et al , 2018).…”

Section: Empirical Expressionsmentioning

confidence: 99%

Efficiency assessment of using graphene nanoplatelets-silver/water nanofluids in microchannel heat sinks with different cross-sections for electronics cooling

Goodarzi

Tlili

Tian

et al. 2019

HFF

104

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Purpose This study aims to model the nanofluid flow in microchannel heat sinks having the same length and hydraulic diameter but different cross-sections (circular, trapezoidal and square). Design/methodology/approach The nanofluid is graphene nanoplatelets-silver/water, and the heat transfer in laminar flow was investigated. The range of coolant Reynolds number in this investigation was 200 ≤ Re ≤ 1000, and the concentrations of nano-sheets were from 0 to 0.1 vol. %. Findings Results show that higher temperature leads to smaller Nusselt number, pressure drop and pumping power, and increasing solid nano-sheet volume fraction results in an expected increase in heat transfer. However, the influence of temperature on the friction factor is insignificant. In addition, by increasing the Reynolds number, the values of pressure drop, pumping power and Nusselt number augments, but friction factor diminishes. Research limitations/implications Data extracted from a recent experimental work were used to obtain thermo-physical properties of nanofluids. Originality/value The effects of temperature, microchannel cross-section shape, the volume concentration of nanoparticles and Reynolds number on thermal and hydraulics behavior of the nanofluid were investigated. Results are presented in terms of velocity, Nusselt number, pressure drop, friction loss and pumping power in various conditions. Validation of the model against previous papers showed satisfactory agreement.

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Effect of thermo-mechanical non-equilibrium on the onset of transition in supersonic boundary layers

Cited by 9 publications

References 22 publications

Control of oblique breakdown in a supersonic boundary layer employing a local cooling strip

Control of oblique breakdown in a supersonic boundary layer employing a local cooling strip

On the Scope of Lagrangian Vortex Methods for Two-Dimensional Flow Simulations and the POD Technique Application for Data Storing and Analyzing

Efficiency assessment of using graphene nanoplatelets-silver/water nanofluids in microchannel heat sinks with different cross-sections for electronics cooling

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