论文标题
完全发育的湍流及其欧拉分解中的拉格朗日加速度
Lagrangian acceleration in fully developed turbulence and its Eulerian decompositions
论文作者
论文摘要
我们通过使用良好解决的各向同性湍流的直接数值模拟对流体颗粒加速度的各种贡献的特性，其网格分辨率高达$ 12288^3 $，而泰勒级雷诺（Taylor-Scale Reynolds）在140到140和1300之间的范围范围内的范围为范围范围范围范围范围，taylor-cale reynolds $r_λ$。 $r_λ$，与简单的理论论点一致，但与Kolmogorov的假设以及Eulerian多重模型的现象学预测有很大差异。局部加速度的缩放也为线性$r_λ$对领先顺序，但详细范围更为复杂。正如Buaria \＆sreenivasan最近所示，局部和对流加速度之间的强烈取消（忠于随机扫描假设的忠实于随机的假设）仅以$r_λ^{0.25} $的增加而增加。莱特牧师。 128，234502（2022）]。加速度差异主要由无关压力梯度贡献支配，其方差也遵循$r_λ^{0.25} $缩放；螺线管粘性贡献相对较小，并遵循$r_λ^{0.13} $，与Eulerian多重预测一致。
We study the properties of various Eulerian contributions to fluid particle acceleration by using well-resolved direct numerical simulations of isotropic turbulence, with the grid resolution as high as $12288^3$ and the Taylor-scale Reynolds number $R_λ$ in the range between 140 and 1300. The variance of convective acceleration, when normalized by Kolmogorov scales, increases linearly with $R_λ$, consistent with simple theoretical arguments, but very strongly differing from phenomenological predictions of Kolmogorov's hypothesis as well as Eulerian multifractal models. The scaling of the local acceleration is also linear $R_λ$ to the leading order, but more complex in detail. The strong cancellation between the local and convective acceleration -- faithful to the random sweeping hypothesis -- results in the variance of the Lagrangian acceleration increasing only as $R_λ^{0.25}$, as recently shown by Buaria \& Sreenivasan [Phys. Rev. Lett. 128, 234502 (2022)]. The acceleration variance is dominated by irrotational pressure gradient contributions, whose variance also follows an $R_λ^{0.25}$ scaling; the solenoidal viscous contributions are relatively small and follow a $R_λ^{0.13}$, consistent with Eulerian multifractal predictions.
