Contribution of direct numerical simulation to understanding and modelling turbulent transport

Kasagi, Nobuhide; Shikazono, Naoki

doi:10.1098/rspa.1995.0125

Cited by 48 publications

(8 citation statements)

References 74 publications

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“…Qualitatively, this is in line with literature; see, for instance, Refs. [10,11]. However, it should be noted here that |w h | is also affected by the geometry.…”

Section: Heat Fluxesmentioning

confidence: 88%

Characteristics of turbulent heat transfer in an annulus at supercritical pressure

et al. 2017

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Heat transfer to fluids at supercritical pressure is different from heat transfer at lower pressures due to strong variations of the thermophysical properties with the temperature. We present and analyze results of direct numerical simulations of heat transfer to turbulent CO 2 at 8 MPa in an annulus. Periodic streamwise conditions are imposed so that mean streamwise acceleration due to variations in the density does not occur. The inner wall of the annulus is kept at a temperature of 323 K, while the outer wall is kept at a temperature of 303 K. The pseudocritical temperature T pc = 307.7 K, which is the temperature where the thermophysical properties vary the most, can be found close to the inner wall. This work is a continuation of an earlier study, in which turbulence attenuation due to the variable thermophysical properties of a fluid at supercritical pressure was studied. In the current work, the direct effects of variations in the specific heat capacity, thermal diffusivity, density, and the molecular Prandtl number on heat transfer are investigated using different techniques. Variations in the specific heat capacity cause significant differences between the mean nondimensionalized temperature and enthalpy profiles. Compared to the enthalpy fluctuations, temperature fluctuations are enhanced in regions with low specific heat capacity and diminished in regions with a large specific heat capacity. The thermal diffusivity causes local changes to the mean enthalpy gradient, which in turn affects molecular conduction of thermal energy. The turbulent heat flux is directly affected by the density, but it is also affected by the mean molecular Prandtl number and attenuated or enhanced turbulent motions. In general, enthalpy fluctuations are enhanced in regions with a large mean molecular Prandtl number, which enhances the turbulent heat flux. While analyzing the Nusselt numbers under different conditions it is found that heat transfer deterioration or enhancement can occur without streamwise acceleration or mixed convection conditions. Finally, through a combination of a relation between the Nusselt number and the radial heat fluxes, a quadrant analysis of the turbulent heat flux, and conditional averaging of the heat flux quadrants, it is shown that heat transfer from a heated surface depends on the density and the molecular Prandtl number of both hot fluid moving away from a heated surface as well as the thermophysical properties of relatively cold fluid moving towards it.

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“…Qualitatively, this is in line with literature; see, for instance, Refs. [10,11]. However, it should be noted here that |w h | is also affected by the geometry.…”

Section: Heat Fluxesmentioning

confidence: 88%

Characteristics of turbulent heat transfer in an annulus at supercritical pressure

et al. 2017

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“…For the case of strongest heating, near the heated wall, a saturation of the spanwise wavelength of the streaky system could be observed. Studies on turbulent channel flows by computations [24][25][26][27][28][29][30], and by experiments [31][32][33][34] have been carried out, since the earlier DNS [20] indicated that turbulent statistics along the wall bisectors agrees well with plane channel data despite the influence of the sidewalls in the former flow.…”

Section: Introductionmentioning

confidence: 93%

Numerical study of forced turbulent heat convection in a straight square duct

Yang

Chen

Zhu

2009

International Journal of Heat and Mass Transfer

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“…They found that the numerical simulation of TBLs is very sensitive to, e.g. proper inflow condition, sufficient settling length and appropriate box dimensions, and hence a DNS has to be considered as a numerical experiment governed by the chosen simulation set-up (Kasagi and Shikazono, 1995). For further progress in the investigation of these characteristics of TBLs, it is required the availability of accurate and reliable high-resolution DNS data for spatially developing TBLs with various numerical set-up such as inflow boundary condition, box dimensions and others.…”

Section: Introductionmentioning

confidence: 99%