Spreading of granular pastes: from the particle to end use properties

作为高度浓缩的颗粒悬浮体的颗粒状浆料，例如石膏浆料和新鲜混凝土，在建筑、化学和食品工业中的不同产品的制造中发挥重要作用。这些材料是非牛顿流体，其复杂的流变特性（屈服应力、触变性）需要用基于物理的模型来理解和描述，以优化这些产品与其配方相关的最终用途特性。优化糊剂的流动行为的一种可能性是施加机械振动以有针对性地控制其粘度。在本合作计画中，我们将联合收割机结合实验与数值工具来研究振动影响下颗粒状浆体的流动行为。在微观尺度上，可以得到微观过程的特征参数以及相之间（颗粒-颗粒、颗粒-流体、颗粒-壁面和流体-壁面）的相互作用。颗粒将在离散单元法（DEM）的帮助下进行模拟。为了考虑液体和颗粒之间的微观相互作用，DEM将与CFD方法相结合。这些模型将在粒子加工工程研究所（德国凯泽斯滕大学）开发。它们将通过在LEMTA实验室（洛林大学，南希，法国）进行的流变学实验进行验证。基于实验和数值计算结果，我们将能够识别的剪切流，颗粒传输和能量耗散的机制，提供的参数，可用于物理模型的宏观尺度。借助一个多尺度模型，可以获得有关振动过程中微观过程对颗粒状糊状物宏观流动行为影响的详细信息。这可用于控制配方的颗粒糊剂的铺展性能的优化。

Granular pastes as highly concentrated particle suspensions, such as gypsum pastes and fresh concretes, play an important role in the manufacturing of different products in the construction, chemical and food industries. These materials are non-Newtonian fluids whose complex rheological properties (yield stress, thixotropy) need to be understood and described with physical based models to optimize the end-use properties of these products in connection with their formulation. One possibility to optimize the flow behavior of the pastes is to apply mechanical vibration for targeted control of their viscosity. In this cooperation project, we will combine the experimental and numerical tools to investigate the flow behavior of granular pastes under influence of vibration. On the microscale the characteristic parameters of the micro processes and the interactions between phases (particle-particle, particle-fluid, particle-wall and fluid-wall) will be obtained. The particles will be simulated with the help of the Discrete Element Method (DEM). To consider the micro interactions between the liquid and particles the DEM will be coupled with a CFD approach. These models will be developed at the Institute of Particle Process Engineering (University of Kaiserslautern, Germany). They will be validated with the rheological experiments performed at LEMTA laboratory (University of Lorraine, Nancy, France). Based on the experimental and numerical results we will be able to identify the mechanisms of the shear flow, particle transport and energy dissipation to provide the parameters that can be used in physical models on the macroscale. With the help of a developed multiscale model, it will be possible to obtain detailed information about the influence of the microprocesses on the macroscopic flow behavior of the granular pastes during vibration. This can be used for the optimization of the spreading properties of granular paste with controlled formulation.