Corrections for underresolved scalar measurements in turbulent flows using a DNS database

被引:0
作者
Paolo Burattini
Maxime Kinet
Daniele Carati
Bernard Knaepen
机构
[1] Université Libre de Bruxelles,Physique Statistique et des Plasmas
来源
Experiments in Fluids | 2007年 / 43卷
关键词
Dissipation Rate; Direct Numerical Simulation; Isotropic Turbulence; Scalar Dissipation; Scalar Dissipation Rate;
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摘要
We estimate the effect of finite spatial resolution of a probe for scalar measurements, using a database from direct numerical simulations (DNS). These are for homogeneous isotropic turbulence in temporal decay, Schmidt number unity, and low Taylor-microscale Reynolds number (≃27–42). The probe could be a cold wire for measuring temperature in a turbulent flow. Correction factors for the scalar variance, scalar dissipation rate, and mixed velocity-scalar derivative skewness are estimated, for a sensor length up to 15 times the Batchelor length scale. It is shown that the lack of resolution yields the largest attenuation on the dissipation rate, followed by the scalar variance. On the contrary, the mixed skewness, which is affected the least, is overestimated. Further, it is shown that if one estimates the mixed skewness via the scalar variance dynamical equation and neglects the term involving the time derivative of the scalar energy spectrum, large errors in the correction factor of the mixed skewness are introduced. Finally, it is found that correction factors obtained assuming Kraichnan scalar model spectrum and following Wyngaard (in Phys Fluids 14:2052–2054, 1971) approach are close to those from the DNS.
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页码:31 / 37
页数:6
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