Direct numerical simulation of dynamic aggregate migration in fresh concrete using multi-scale Smoothed-Particle Hydrodynamics

使用多尺度平滑粒子流体动力学直接数值模拟新拌混凝土中的动态骨料迁移

• 批准号: 387152355
• 负责人: Professor Dr.-Ing. Holger Steeb
• 金额: --
• 依托单位: Lehrstuhl für Kontinuumsmechanik
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/387152355?language=en
• 关键词: Direct; numerical; simulation; dynamic; aggregate

The scientific objectives of the proposed research project within the SPP 2005 aim towards improving our understanding of graded fresh concrete flow in confined geometries using microstructure-resolved SPH simulations. In this regard, special attention will be devoted to shear-induced particle migration and lubrication layer formation processes motivated by their technological significance for concrete pumping. As these processes take place at length scales which are significantly smaller than the engineering length scale, resolved surface-coupled Direct Numerical Simulations (DNS) are considered appropriate approaches. In order to address the significant computational requirements of DNS, high-performance computing approaches will be used (massively parallel distributed memory computing). Our simulation approach shall explicitly take into account the multi-scale nature of fresh concrete in that the rheology of the carrier fluid as well as the numerically resolved aggregate content can be adaptively modified to adequately represent the dominating mechanisms at a suitable length and time scale. Given our interest in particle migration processes, characteristic time scales we attempt to represent in our simulations will be in the order of particle self-diffusion times. In other words, simulated time scales must be sufficient to study shear-induced dynamic aggregate segregation processes in graded concrete suspensions. This implies that our simulations will strongly be separated from time-scales associated with the chemical reactivity of hydrating cement suspensions. As a result, this project focuses on the evolution of fresh concrete microstructure during flow, i.e. resulting in segregation effects such as heterogeneous particle size and concentration distributions, due to hydrodynamic and tribological effects. Our scientific work program shall be tailored in such a way that our simulation results can ultimately provide a reliable data and knowledge basis to develop coarse-grained macroscopic models of fresh concrete flow during pumping. This data basis shall cover a feature space composed of mix design and boundary conditions. In that respect, the anticipated output of the present project is considered a valuable input to module 3 of the SPP 2005. A computationally optimized simulation framework for SPH simulations is available. This simulation framework is based on HOOMD-blue (Highly Optimized Object-oriented Many-particle Dynamics) and has previously proven good parallel performance on computer clusters we have access to. Core algorithms related to the simulation of arbitrary-shaped rigid particles suspended in continuous carrier liquids (e.g. data structures, time integration routines) have been implemented. Within the duration of the proposed project, comparatively little time will thus be devoted to software implementation.

SPP 2005中提出的研究项目的科学目标旨在通过使用微观结构分辨的SPH模拟来改善我们对狭窄几何形状的分级新鲜混凝土流的理解。在这方面，特别注意将剪切诱导的颗粒迁移和润滑层形成过程，其技术因其对混凝土泵的意义而激发。由于这些过程以长度比工程长度尺度小得多的长度尺度进行，因此已解决的表面耦合直接数值模拟（DNS）被视为适当的方法。为了满足DNS的重要计算要求，将使用高性能计算方法（大规模平行的分布式内存计算）。我们的仿真方法应明确考虑新鲜混凝土的多尺度性质，因为载体流体的流变以及数值分辨的聚合含量可以自适应地修改以充分代表适当长度和时间尺度的统治机制。鉴于我们对粒子迁移过程的兴趣，我们尝试在模拟中表示的特征时间尺度将按照粒子自扩散时间的顺序。换句话说，模拟的时间尺度必须足以研究分级混凝土悬浮液中剪切诱导的动态聚集分离过程。这意味着我们的模拟将与与水合水泥悬浮液的化学反应性相关的时间尺度分开。结果，该项目的重点是流动过程中新鲜混凝土微观结构的演变，即由于流体动力和摩擦学效应，导致隔离效应，例如异质粒径和浓度分布。我们的科学工作计划应以这样的方式量身定制，使我们的仿真结果最终可以提供可靠的数据和知识基础，以在抽水过程中开发新鲜混凝土流的粗粒宏观模型。该数据基础应涵盖由混合设计和边界条件组成的特征空间。在这方面，本项目的预期输出被认为是SPP 2005模块3的有价值的输入。可用于SPH模拟的计算优化仿真框架。该仿真框架基于HOOMD-Blue（高度优化的对象的多个粒子动力学），并以前证明了我们可以访问的计算机簇上的良好并行性能。已经实施了与悬浮在连续载体液体中的任意形状的刚性颗粒有关的核心算法（例如，数据结构，时间整合例程）。在拟议项目的持续时间内，相对较少的时间将用于软件实施。