This paper develops an arbitrary-positioned buffer for the smoothed particle hydrodynamics (SPH) method, whose generality and high efficiency are achieved through two techniques. First, with the local coordinate system established at each arbitrary-positioned in-/outlet, particle positions in the global coordinate system are transformed into those in it via coordinate transformation. Since one local axis is located perpendicular to the in-/outlet boundary, the position comparison between particles and the threshold line or surface can be simplified to just this coordinate dimension. Second, particle candidates subjected to position comparison at one specific in-/outlet are restricted to those within the local cell-linked lists nearby the defined buffer zone, which significantly enhances computational efficiency due to a small portion of particles being checked. With this developed buffer, particle generation and deletion at arbitrary-positioned in- and outlets of complex flows can be handled efficiently and straightforwardly. We validate the effectiveness and versatility of the developed buffer through 2-D and 3-D non-/orthogonal uni-/bidirectional flows with arbitrary-positioned in- and outlets, driven by either pressure or velocity boundary conditions.

翻译：本文为光滑粒子流体动力学方法开发了一种任意位置缓冲器，其通用性和高效率通过两种技术实现。首先，在每个任意位置的入口/出口处建立局部坐标系，通过坐标变换将全局坐标系中的粒子位置转换至该局部坐标系中。由于局部坐标系的一个坐标轴垂直于入口/出口边界，粒子与阈值线或面的位置比较可简化为仅在此坐标维度上进行。其次，在特定入口/出口处需要进行位置比较的候选粒子被限制在定义缓冲区附近的局部单元链表内，由于仅需检查少量粒子，这显著提升了计算效率。利用所开发的缓冲器，可高效直接地处理复杂流动中任意位置入口和出口处的粒子生成与删除。我们通过压力或速度边界条件驱动的二维与三维非正交/正交单向/双向流动（含任意位置入口和出口）验证了所开发缓冲器的有效性和通用性。