This study develops a computationally efficient phase-field lattice Boltzmann model with the capability to simulate thermocapillary flows. The model was implemented into the open-source simulation framework, waLBerla, and extended to conduct the collision stage using central moments. The multiphase model was coupled with both a passive-scalar thermal LB, and a RK solution to the energy equation in order to resolve temperature-dependent surface tension phenomena. Various lattice stencils (D3Q7, D3Q15, D3Q19, D3Q27) were tested for the passive-scalar LB and both the second- and fourth-order RK methods were investigated. There was no significant difference observed in the accuracy of the LB or RK schemes. The passive scalar D3Q7 LB discretisation tended to provide computational benefits, while the second order RK scheme is superior in memory usage. This paper makes contributions relating to the modelling of thermocapillary flows and to understanding the behaviour of droplet capture with thermal sources analogous to thermal tweezers. Four primary contributions to the literature are identified. First, a new 3D thermocapillary, central-moment phase-field LB model is presented and implemented in the open-source software, waLBerla. Second, the accuracy and computational performance of various techniques to resolve the energy equation for multiphase, incompressible fluids is investigated. Third, the dynamic droplet transport behaviour in the presence of thermal sources is studied and insight is provided on the potential ability to manipulate droplets based on local domain heating. Finally, a concise analysis of the computational performance together with near-perfect scaling results on NVIDIA and AMD GPU-clusters is shown. This research enables the detailed study of droplet manipulation and control in thermocapillary devices.

翻译：本研究开发了一种计算高效的相场晶格玻尔兹曼模型，能够模拟热毛细流动。该模型被集成到开源仿真框架waLBerla中，并扩展为采用中央矩进行碰撞阶段计算。多相模型与被动标量热LB以及能量方程的龙格-库塔（RK）求解方法耦合，以解析与温度相关的表面张力现象。针对被动标量LB测试了多种晶格模板（D3Q7、D3Q15、D3Q19、D3Q27），并研究了二阶和四阶RK方法。LB与RK方案在精度上未观察到显著差异。被动标量D3Q7 LB离散化在计算性能上具有优势，而二阶RK方案内存占用更优。本文在热毛细流动建模以及理解类似热镊子的热源液滴捕获行为方面作出了贡献。主要贡献包括四个方面：第一，提出了一种新的三维热毛细中央矩相场LB模型，并在开源软件waLBerla中实现；第二，研究了求解多相不可压缩流体能量方程的不同技术的精度与计算性能；第三，分析了热源存在下的动态液滴输运行为，揭示了基于局部区域加热操控液滴的潜在能力；最后，通过NVIDIA和AMD GPU集群上的近完美扩展性结果，对计算性能进行了简洁分析。本研究为热毛细器件中液滴操控与控制的精细化研究提供了支持。