论文标题
朝着湍流泰勒气泡流的直接数值模拟
Towards direct numerical simulation of turbulent co-current Taylor bubble flow
论文作者
论文摘要
本文提出了湍流泰勒气泡流的DNS的模拟策略。这是[2]中提出的工作的延续,其中提出了大型涡流湍流泰勒气泡流的大型涡流模拟(LES)。据观察,主要挑战之一是对泰勒气泡裙的行为的物理准确预测和相关的气泡脱落。在LES结果中观察到泰勒气泡后的湍流波动的低估。有人提出,这与泰勒气泡损失的过度预测是由于由Les网状分辨率引起的气泡脱落而导致的,这不足以准确捕获破裂和气泡形成。为了解决这个问题,在当前的工作中,我们基于带有局部自适应网格细化的Basilisk代码,提出了称为RK-Basilisk的共流湍流泰勒气泡流的DNS方法。该策略允许在气泡的界面附近提供很高的网格分辨率,而在其他地方则允许网格更粗糙。每个时间步骤,基于空隙分数标准对网格进行调整。基于“ OCTREE”的Basilisk的基础数据结构允许更快的解决方案程序,因此与使用更通用的OpenFOAM代码执行的LES模拟相比,更多的网格点。我们将结果与同一设置的实验数据以及共同流动的LES OpenFOAM结果进行了比较。在共流条件下湍流泰勒气泡流的设置既可以允许较低阶段的湍流模型发展和更一般的两相建模策略的验证。泰勒气泡流本身也与特定的两相流动情况相关。当前的工作有助于进步这种情况。
This paper present a simulation strategy for DNS of turbulent co-current Taylor bubble flow. This is a continuation of the work presented in [2] in which Large Eddy Simulation (LES) of co-current turbulent Taylor bubble flow was presented. It was observed that one of the main challenges is the physically accurate prediction of the behavior of the Taylor bubble skirt, and the related bubble shedding. An underestimation of the turbulent fluctuations in the wake of the Taylor bubble was observed in the LES results. It was suggested that this is related to over-prediction of the loss of void of the Taylor bubble due to bubble shedding induced by an LES mesh resolution which is not sufficient to capture the break-up and bubble formation accurately. To counter this, in the current work we present a DNS approach of co-current turbulent Taylor bubble flow called RK-Basilisk, based on the Basilisk code with local adaptive grid refinement. This strategy allows for very high mesh resolution near the bubble's interface while elsewhere the grid is allowed to be coarser. Each time step, the mesh is adapted based on a void fraction criterion. Basilisk's underlying data structure which is based on an 'octree' allows for much faster solution procedures and, therefore, a much greater number of grid points as compared to the LES simulations which were performed using the more general OpenFOAM code. We compare the results against experimental data of the same setting, as well as the co-current LES OpenFOAM results. The setting of turbulent Taylor bubble flow in co-current conditions allows for both lower order turbulence model development and the validation of more general two-phase modeling strategies. Taylor bubble flow in itself also bears relevance to specific two-phase flow situations. The current work contributes to an advancement in simulation capability for such situations.