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Description
The two-phase flow study is meaningful for mass transfer in various industrial processes, for example the prediction of proppant distribution is of significance due to the fact that proppant placement contributes to the enhanced production of fluids by affecting the conductivity of the fractured reservoir. Since it is difficult and expensive for experiments to consider various conditions and detect the movement of every particle, numerical simulation methods are often applied. For more precise simulations, the simplified fracture geometry and soft sphere particle model is used. The coupled CFD-DEM (Computational Fluid Dynamics-Discrete Element Method) approach is implemented in this work to compute proppant transport and settlement in a specific configuration. The DEM is employed to assess particle-particle and particle-geometry interactions, while the CFD is used to describe the flow field. The comparison of simulation results shows that the profile of the particle bed produced by the CFD-DEM is consistent with those derived from experiments. The proppant motion is captured in detail during transport to interpret the transport mechanism at the particulate scale. Once separated from the suspending layer, particles first accelerate, then decelerate, with dramatic rolling; meanwhile, both velocity and angular velocity slow down and finally stop. The asymmetry of fractures in the vertical direction is common due to lithologic heterogeneity. The effect of the injection position cannot be neglected. Thus, cases where particles of different densities are injected at three different injection heights are simulated. It is shown that the separation of particles is conditional and the difference in density is not the dominant factor. This separation is the most obvious, and the area covered is maximized, when low-density particles are injected from a higher inlet.
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