Turbulent structure in solid-liquid flow and the simulation model on particle motion in this flow

用概率密度分布的方法研究了对浓度分布和湍流能量的产生起重要作用的抛射的侵彻深度。两相流比单相流的深度小，固体颗粒在喷射时的深度比单相流的深度小得多。这些差异被认为是由固体颗粒的松弛过程及其对流动的反应造成的。通过对流动中颗粒运动的分析，证明了这一猜想。我们得到了包含Stokes阻力和Basset项的中性浮力粒子运动的积分-微分方程的精确解。与仅在斯托克斯阻力情况下的指数分布相反，该解在渐近膨胀中表现为-lt；t^(-1/2)&gt；。弹射时垂直速度的概率密度分布在壁面附近有两个峰值。建立了抛射过程与湍流扩散分离过程中浓度分布的简单模拟模型。在扩散方程中，抛射过程被视为一个周期对流项。该模型的计算结果与实验结果吻合较好，尤其是在壁面附近。

Penetration depth on an ejection, which played an important role in the formation of concentration profile and generation of turbulent energy, was studied by means of a probability density distribution. The depth in a two phase flow was smaller than a single phase flow, the depth of a solid particle at the ejection was much smaller than that. These difference was supposed to be caused by the relaxation process of a solid particleand its reaction on the flow. This conjecture was made clear by the analysis of a particle motion in the flow. We had an exact solution on the integro-differential equation of motion of a neutrally buoyant particle, involved Stokes resistance and Basset term. This solution behaved <t^(-1/2)> in assymptotic expansion, in contrast to the exponential behavior in the case of Stokes resistance only.The probability density distribution of vertical velocities at ejection had two peaks near the wall. This results showed the possibility of the existence of different mechanism on the generation of ejection.The simple simulation model on the concentration profilewas constructed in the separation of ejection process from turbulent diffusion. The ejection process was treated as a periodically convective term in the diffusion equation. the results of this model were fairly in the agreement with the results of experiment, especially near the wall.