SGER: Multiscale Modeling of Fluctuating Hydrodynamics with Energy Conservation

提案编号：CBET-0741359主要研究员：乔瑞所属：克莱姆森大学提案标题：SGER：具有能量守恒的脉动流体多尺度模型颗粒悬浮液和聚合物流体中的热输运在许多工程系统中起着至关重要的作用。当颗粒尺寸较大时，经典流体力学理论已经成功地描述了这种体系中的热输运，但当颗粒尺寸减小到纳米尺度时，经典流体力学理论可能会变得不再适用。具体地说，热波动会对系统中的热输运产生很大影响，因此必须采用脉动流体动力学。然而，以热力学自洽的方式将热涨落引入非等温模拟具有极大的挑战性，目前几乎没有有效的算法可用。本项目的目标是开发一个新的多尺度模拟框架，用于模拟具有能量守恒的脉动流体动力学。在该框架中，原子尺度、介观尺度和宏观尺度上的热输运分别用分子动力学(MD)、能量守恒耗散粒子动力学(EDPD)和经典计算流体力学方法来模拟。在这样的框架下，纳米粒子的介观涨落和流场被显式地以热力学自洽的方式建模。EDPD模型通过分子动力学模拟进行参数化，也可以通过直接耦合与经典流体动力学模拟相联系。我们将研究如何将原子细节结合到eDPD模型中，以实现跨不同长度尺度的热传输模型的无缝集成。我们还将直接将物理化学相互作用引入eDPD模型，以更真实地描述颗粒相互作用。开发的代码将通过将模拟结果与选定系统的现有实验结果进行比较来进行测试。最后，我们将探索聚合物接枝微通道中热传输的建模。智能优点：所提出的多尺度建模技术将为脉动流体动力学和复杂流体的建模增加新的武器库。该技术是有效的，因为消除了与网格划分具有移动边界的系统相关的繁重的计算成本。该技术的粒子性质也使复杂粒子形状的建模变得简单。因此，新的建模框架所提供的计算效率和灵活性将能够有效地对一大类输送过程进行建模，在这类输送过程中，中尺度波动是重要的。这将有助于阐明这些过程中的中尺度波动的影响，也将有助于发展这些输送过程的宏观模式。研究聚合物接枝通道中的热传递将有助于揭示热波动、聚合物构象和通道内流体流动之间的相互作用，并为优化这类系统中的传热奠定基础。广泛的影响：该项目将为研究生提供机会从事涉及计算物理、复杂流体和热科学的跨学科项目。开发的新的多尺度框架将被记录在同行评价的专业期刊上，以便广泛传播。本项目所获得的仿真结果将以图片和电影的形式在网上展示，用于教学。该网站将通过各种正式和非正式渠道向研究/教育专业人员、本科生/研究生和K-12学生宣传。对基本概念的图形描述，例如粒子的布朗运动，将有助于理解这些概念，并有助于激发学生在STEM学科中进行教育的兴趣。研究成果还将被开发成克莱姆森大学本科计算流体力学课程的教材。

Proposal Number: CBET-0741359Principal Investigator: Qiao, Rui Affiliation: Clemson UniversityProposal Title: SGER: Multiscale Modeling of Fluctuating Hydrodynamics with Energy ConservationThermal transport in particulate suspension and polymeric fluids plays a critical role in many engineering systems. While the classical hydrodynamic theories have been successful in describing thermal transport in such systems when the particulate size is large, they could become inadequate when the particulate size is reduced to nanometer dimension. Specifically, thermal fluctuation may significantly affect the thermal transport in such systems, and thus the fluctuating hydrodynamics must be adopted. However, incorporating thermal fluctuations into non-isothermal simulations in a thermodynamically self-consistent manner is extremely challenging and very few efficient algorithms are available so far.The objective of this project is to develop a novel multiscale simulation framework for modeling of fluctuating hydrodynamics with energy conservation. In the proposed framework, the thermal transport at atomistic, mesoscopic and macroscopic scales are modeled by molecular dynamics (MD), energy-conserving dissipative particle dynamics (eDPD) and classical computational fluid dynamics method, respectively. In such a framework, the mesoscale fluctuations of nanoparticulates and flow field are modeled explicitly in a thermodynamically self-consistent manner. The eDPD model is parameterized by molecular dynamics simulations and can also be linked to classical hydrodynamics simulation via direct coupling. We will investigate how to incorporate atomistic details into the eDPD model to achieve a seamless integration of modeling of thermal transport across disparate length scales. We will also introduce physicochemical interactions directly into the eDPD model for a more realistic description of particulate interactions. The developed codes will be tested by comparing the simulation results against available experimental results for selected systems. Finally, we will explore the modeling of thermal transport in microchannels grafted with polymers.Intellectual Merit: The proposed multiscale modeling technique will add new arsenal to the modeling of fluctuating hydrodynamics and complex fluids. The proposed technique is efficient as the heavy computational cost associated with meshing a system with moving boundaries is eliminated. The particle nature of the technique also renders the modeling of complex particle shape straightforward. The computational efficiency and flexibility provided by the new modeling framework will thus enable the efficient modeling of a broad class of transport processes in which mesoscale fluctuation is important. This will help to elucidate the effects of mesoscale fluctuations in these processes and will also help to develop macro-models for these transport processes. Study of the heat transfer in channels grafted with polymers will shed light on the interactions between thermal fluctuation, polymer conformation and fluid flow in the channel and lay the foundation for optimizing the heat transfer in such systems.Broader Impacts: The project will provide opportunity for a graduate student to work on an interdisciplinary project involving computational physics, complex fluids, and thermal sciences. The novel multiscale framework developed will be documented in peer evaluated professional journals for wide dissemination. Simulation results obtained in this project will be put into pictorial and movie formats and displayed on internet for teaching. The website will be advertised to research/education professionals, undergraduate/graduate student and K-12 students through various formal and informal channels. The graphic description of fundamental concepts, e.g., Brownian motion of particulates, will facilitate the understanding of these concepts and helps to ignite interest of students in pursuing education in STEM discipline. The research results will also be developed into the teaching materials for the undergraduate computational fluid dynamics course at Clemson University.