Research on Turbulent Diffusion from Instantaneous Source of Matter and Its Mathematical Modelling

瞬时物源湍流扩散及其数学模型研究

• 批准号: 08650194
• 负责人: TSUNODA Hiroyuki
• 金额: $ 0.26万
• 依托单位: YAMANASHI UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08650194/
• 关键词: Fluid Engineering; Turbulence; Turbulent Diffusion; Laster Induced Fluorescence; Concentration Measurement; CFD; Stochastic Model; Lagrangian Properties; 確率モデル; 流れの可視化; 画像処理; マルコフ過程

1 . Development of Measurement System of Instantaneous Concentration FieldA method based on Laser-Induced-Fluorescence (LIF) has been adopted for the measurement of instantaneous concentration field of matter in turbulent flow. A preliminary examination has been conducted to select an appropriate fluorescent dye which emits enough strong luminescent light for the incidence laser beam (YAG laser) to realize a high-precision quantitative measurement of instantaneous concentration of dye. Results of the absorption and luminescence spectra showed that Rhodamine B and Rhodamine 6G are most appropriate for our purposes. Furthermore, a good linear relation between the concentration of dye and the luminescence intensity has been found to exist in the range of the concentration less than 1 mg/l These results suggest that our system could be available enough for the measurement of instantaneous concentration of matter.2. Modelling for the Numerical Prediction of Turbulent Diffusion based on Lagrangian MethodA combined method of Eulerian and Lagrangian techniques has been deve1oped for the calculation of statistics of a fluctuating sca1air field in turbulence. In this model, the Eulerian velocities which are obtained by a DNS method are used to compute the Lagrangian trajectories of material particles. Then, concentration statistics are estimated on the basis of stochastic theory for the Markovian process. This method can be applied into a diffusion field with high Prandtl number and any higherorder statistics can be obtained in principle.The effects of the Prandtl number on the scalar dispersion in isotropic homogeneous turbulence have been investigated. It is found that the decay of the scalar variance has a. strong dependence of the Prandtl number whereas the turbulence/scalar time-scale ratio seems to approach to an asymptotic value which is independent of the Prandtl number .

1 .瞬态浓度场测量系统的研制采用激光诱导荧光（LIF）技术测量湍流中物质的瞬态浓度场。为实现染料瞬时浓度的高精度定量测量，对选择合适的荧光染料进行了初步的研究。吸收光谱和荧光光谱的结果表明，罗丹明B和罗丹明6 G是最适合于我们的目的。此外，在染料浓度小于1 mg/l的范围内，染料浓度与发光强度之间存在良好的线性关系，这表明该系统可以用于物质瞬时浓度的测量.基于拉格朗日方法的湍流扩散数值预报模型本文提出了一种欧拉和拉格朗日技术相结合的方法，用于计算湍流中脉动尺度流场的统计特性。在该模型中，欧拉速度是由DNS方法获得的用于计算拉格朗日轨迹的物质颗粒。然后，根据马尔可夫过程的随机理论，对集中统计量进行了估计。该方法适用于具有高Prandtl数的扩散场，原则上可以得到任意高阶统计量，并研究了Prandtl数对各向同性均匀湍流标量色散的影响。研究发现，标量方差的衰减具有a.强的依赖性的普朗特数，而湍流/标量时间尺度比似乎接近一个渐近值，这是独立的普朗特数。

项目成果

鈴木 健: "ラグランジュ的な粒子速度の関係を用いた2粒子対確率過程モデルによる変動スカラー場の数値シミュレーション" 日本機械学会論文集(B編). 64・625. 2828-2835 (1998)

Ken Suzuki：“使用拉格朗日粒子速度关系的双粒子随机过程模型对波动标量场进行数值模拟”日本机械工程师学会会刊（编辑 B）2828-2835（1998 年）。

Hiroyuki TSUNODA: ""Estimation of Scalar Atatistics from Lagrangian Trajectories of Material Particles in Numerically Simulated Turbulence"" Proceedings of the 3rd ASME/JSME Joint Fluids Engineering Conference. (in press). (1999)

Hiroyuki Tsunoda：“数值模拟湍流中物质粒子拉格朗日轨迹的标量统计估计”第三届 ASME/JSME 联合流体工程会议论文集。

Sakai, Y.: "Turbulent Diffusion in the Pipe Flow by the Stochastic Lagrangian Model" Advances in Turbulence (Kluwer Academic Pub.). 7. 547-550 (1998)

Sakai, Y.：“随机拉格朗日模型在管流中的湍流扩散”湍流进展（Kluwer 学术出版社）。

角田 博之: "ラグランジュ手法による数値乱流中一様スカラ場の解析" 日本機械学会関東支部山梨講演会講演論文集. 980-3. 173-174 (1998)

Hiroyuki Tsunoda：“使用拉格朗日方法分析数值湍流中的均匀标量场”日本机械工程师学会关东分会山梨会议记录 980-3（1998）。

Hiroyuki TSUNODA: ""Direct Numerical Simulation of Relative Dispersion of Fluid Particle-Pairs"" Proceeding of the 74th JSME Fall Annual Meeting [Vol.III] (in Japanese). No.96-15. 263-264 (1996)

Hiroyuki TSUNODA：““流体粒子对相对分散的直接数值模拟””第 74 届 JSME 秋季年会论文集 [Vol.III]（日语）。