Computational modeling of multiphase viscoelastic and elastoviscoplastic flows
Computational modeling of multiphase viscoelastic and elastoviscoplastic flows
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DOI：
10.1002/fld.4678
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发表时间：
2018-12-30
影响因子：
1.8
通讯作者：
Tammisola, Outi
中科院分区：
文献类型：
--
作者：
Izbassarov, Daulet;Rosti, Marco E.;Tammisola, Outi
在本文中，开发了一种三维数值求解器，用于解决粘弹性和弹粘塑性（EVP）流体中的刚性和软颗粒和液滴的悬浮液。所提出的算法旨在首次对具有大量颗粒和液滴的惯性和湍流 EVP 流体进行三维模拟。这是通过将快速且高度可扩展的方法（例如基于 FFT 的压力求解器）与非牛顿（包括 EVP）应力的演化方程相结合来实现的。在这个灵活的计算框架中，流体可以通过 Oldroyd-B、neo-Hookean、FENE-P 或 Saramito EVP 模型进行建模，并且非牛顿应力的附加方程与流动完全耦合。刚性粒子在移动拉格朗日网格上离散化，而流动方程在固定欧拉网格上求解。固体颗粒由浸没边界法和计算效率高的直接强迫法表示，允许模拟大量颗粒。浸没边界力在颗粒表面计算，然后作为体力包含在动量方程中。另一方面，液滴和软颗粒在完全欧拉框架中进行模拟，前者使用水平集方法来捕获移动界面，后者使用指示函数。首先通过与文献中的数据进行比较，针对各种基准单相和两相 EVP 流动问题对求解器进行了验证。最后，我们提出了 EVP 流体中浮力驱动的下降动力学的新结果。
In this paper, a three-dimensional numerical solver is developed for suspensions of rigid and soft particles and droplets in viscoelastic and elastoviscoplastic (EVP) fluids. The presented algorithm is designed to allow for the first time three-dimensional simulations of inertial and turbulent EVP fluids with a large number particles and droplets. This is achieved by combining fast and highly scalable methods such as an FFT-based pressure solver, with the evolution equation for non-Newtonian (including EVP) stresses. In this flexible computational framework, the fluid can be modeled by either Oldroyd-B, neo-Hookean, FENE-P, or Saramito EVP models, and the additional equations for the non-Newtonian stresses are fully coupled with the flow. The rigid particles are discretized on a moving Lagrangian grid, whereas the flow equations are solved on a fixed Eulerian grid. The solid particles are represented by an immersed boundary method with a computationally efficient direct forcing method, allowing simulations of a large numbers of particles. The immersed boundary force is computed at the particle surface and then included in the momentum equations as a body force. The droplets and soft particles on the other hand are simulated in a fully Eulerian framework, the former with a level-set method to capture the moving interface and the latter with an indicator function. The solver is first validated for various benchmark single-phase and two-phase EVP flow problems through comparison with data from the literature. Finally, we present new results on the dynamics of a buoyancy-driven drop in an EVP fluid.