Transient dynamics of fracturing media has received significant attention in recent years, and a number of simulation approaches have been developed. One of these is the combined finite-discrete element method (FDEM). FDEM produces complex fracture and fragmentation patterns in processes such as blast loads, blasting, impact, mining, and oil exploration. To address a wide range of multi-physics problems, numerous approaches have been undertaken to introduce fluid into the FDEM transient dynamics, ranging from application-specific gas models to more advanced hydraulic fracture processes and biomedical applications. None of these have been satisfactory in terms of robustness, accuracy or computational efficiency. In this work, a completely new explicit fluid solver has been tailor-made and fully integrated (as opposed to coupled) into the combined finite-discrete element method. The solver addresses transient pressure wave propagation in fluid, fluid viscosity, equation of state for the fluid, energy transport, momentum transport, and interaction with the fracturing solid domains, which is done through a novel immersed boundary approach. The solver is based on the governing equations being resolved using different control volume schemes, with discretization errors of either third, second, or first order. The solver is fully explicit and conditionally stable with a time step that is synchronized with the FDEM’s time step.

近年来，压裂介质的瞬态动力学受到了广泛的关注，并且已经开发了许多模拟方法。其中之一是组合有限元法（FDEM）。FDEM在爆炸载荷，爆破，冲击，采矿和石油勘探等过程中产生复杂的断裂和破碎模式。为了解决广泛的多物理场问题，已经采取了多种方法将流体引入FDEM瞬态动力学中，从特定的气体模型到更高级的水力压裂过程和生物医学应用。在鲁棒性，准确性或计算效率方面，这些都不令人满意。在这项工作中 量身定制了一种全新的显式流体求解器，并将其完全集成（而不是耦合）到组合的有限元法中。求解器解决了瞬态压力波在流体中的传播，流体的粘度，流体的状态方程，能量传输，动量传输以及与压裂固体域的相互作用，这是通过一种新颖的浸入边界方法来完成的。求解器基于使用不同控制体积方案求解的控制方程，离散误差为三阶，二阶或一阶。求解器是完全明确的，并且其条件步长与FDEM的时间步长同步。能量传输，动量传输以及与压裂固体域的相互作用，这是通过一种新颖的沉浸边界方法完成的。求解器基于使用不同控制体积方案求解的控制方程，离散误差为三阶，二阶或一阶。求解器是完全明确的，并且其条件步长与FDEM的时间步长同步。能量传输，动量传输以及与压裂固体域的相互作用，这是通过一种新颖的沉浸边界方法完成的。求解器基于使用不同控制体积方案求解的控制方程，离散误差为三阶，二阶或一阶。求解器是完全明确的，并且其条件步长与FDEM的时间步长同步。