纳米流体在圆管中输运的两相流理论模型及黏度计算

A two-phase flow theoretical model of nanofluid flowing in pipe and viscosity calculation

基于Fokker-Planck方程与流体动量方程,建立了压力驱动纳米流体在园管中输运的两相流藕合理论模型,模型考虑了纳米粒子的相互碰撞效应、布朗运动效应以及纳米粒子与液体的相互耦合作用,本文所建立的模型没有引入任何唯象参数,与以往的唯象模型相比较,理论上更完备,采用该模型对纳米流体的黏度随温度、纳米粒子体积分数以及粒子尺度的变化规律进行了预测,结果表明,在高粒子体积分数下,纳米流体剖面速度分布呈"柱塞"状,这与单相流体剖面速度呈抛物线分布有明显的差异,该模型预测的黏度在较大范围内均与实验结果很好的吻合.

A coupled two-phase flow transport theoretical model of the nanofluid flowing in a tube is proposed,which is based on the Fokker-Planck equation and the fluid momentum equation.This model takes into account the effects of the Brownian motion of nanoparticles,the interaction between nanoparticles and the interaction between nanoparticles and fluid.This model does not introduce any empirical parameters.Compared with the previous phenomenological models,this model is more complete in theory.The variation of nanofluid viscosity with condition of temperature,particle size and nanoparticle’s volume fraction is predicted.It is shown that,in high volume fraction,the velocity distribution of nanofluid is shown as a ＂cork-shaped＂ structure,this is significantly different from single-phase viscous fluid with a parabolic distribution.And the viscosity of nanofluid is in good agreement with the experimental result in a wide range.