Abstract: Extensive research on the liquid-solid two-phase transportation in horizontal circular tubes has been conducted, but the liquid-solid two-phase hydrodynamics and the solid phase diffusion characteristics in narrow rectangular channels are rarely reported. The glass beads-water two-phase hydrodynamics in horizontal narrow rectangular channel with 12mm height are investigated by the approach of experimental method and CFD-DEM simulation. The pressure gradient characteristics, the solid phase flow characteristics, the statistical properties, and the solid phase diffusion characteristics are explored. Simulation results showed that a dilute disperse phase and a dense cluster phase were formed in the process of solid movement. The dense cluster phase is elevated and accelerated along the horizontal direction. Increasing solid concentration can reduce the non-uniform degree of the solid distribution while enhance the asymmetry of the solid vertical velocity profiles. The vertical solid dispersion intensity can be suppressed with the increase of the solid concentration. Three distinct regions are identified along the vertical direction, corresponding to the near-wall region, the solid highly-collisional region, and the dilute particle-laden region, respectively. The viscous-turbulent interface interacts with the particles in the near-wall region, which drives the particles away from the bottom wall and thus leads to the greatest standard variances of the solid stream-wise velocity and the solid concentration. In the solid highly-collisional region, the fluctuation of the solid vertical velocity is larger because of the chaos motion than that in two other regions. The standard variances of the solid stream-wise velocity and the solid concentration keep little change in the solid highly-collisional flow region and then decay rapidly to zero in the dilute particle-laden region.

Key words: CFD-DEM, liquid-solid, horizontal narrow rectangular channel

摘要： 液固两相输运研究主要集中于圆管，窄矩形通道内液固两相水平流动特性和固相扩散特性的研究鲜见报道。在12mm高的水平窄矩形通道内，采用实验研究和计算流体力学-离散单元法（CFD-DEM）数值模拟相结合的方法研究了玻璃珠-水液固两相流动，揭示了压力梯度特性、固相流动特性及其统计学特性、固相扩散特性变化规律。结果表明：在固相运动过程中，形成稀密两相共存的流动结构，密相在水平方向上被加速且向上运动；随着固相浓度增加，固相沿垂向的分布更加均匀，但固相速度非对称分布增强；固相垂向扩散强度随固相浓度增加而减弱。沿垂向将流道分为3个区域：近壁区、颗粒高频碰撞区和颗粒稀疏区。在近壁区，黏性底层-湍流层交界面与颗粒相互作用并将颗粒向流道中心挤压，导致沿流向的固相速度分量和固相体积分散波动较大；在颗粒高频碰撞区，在垂直方向上颗粒无序运动造成其垂向速度分量波动比近壁区和颗粒稀疏区的大；沿流向的固相速度分量和固相体积分数标准差值在整个颗粒高频碰撞区内保持在较小的变化范围，然后在颗粒稀疏区内迅速降低为零。

关键词: 计算流体力学-离散单元法, 液固, 水平窄矩形通道