Bubbly turbulent flow in a channel is investigated using interface-resolved direct numerical simulation. An efficient coupled level-set volume-of-fluid solver based on a fast Fourier transform algorithm is implemented to enable a high resolution and fast computation at the same time. Up to 384 bubbles are seeded in the turbulent channel flow corresponding to 5.4% gas volume fraction. Bubbles are clustered in the channel center due to the downward flow direction. The bubbles induce additional pseudo-turbulence in the channel center and are also able to attenuate the energy in the boundary layer by reducing the shear production. Turbulent kinetic energy budget indicates a significant buoyancy production in the channel center. A local equilibrium between buoyancy production and dissipation is observed here besides the shear production peak in the boundary layer. Comparing the local production and dissipation indicates a coexistence of boundary layer turbulence near the wall and bubble-induced pseudo-turbulence in the channel center. The liquid phase and gas phase are coupled through the complex liquid–gas interface. Local flow topology analysis is depicted in the liquid phase around the bubbles as well as in the gas phase. The flow topology of the liquid phase and the gas phase differs from each other significantly. Local dissipation is more dominant in the liquid phase near the bubble interface, whereas local enstrophy is preferred in the gas phase. In the liquid phase, a high dissipation event is preferred close to the interface, whereas a high enstrophy event is dominant away from the interface.

中文翻译：

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分散气泡流中的湍流、伪湍流和局部流动拓扑

使用界面分辨直接数值模拟研究了通道中的气泡湍流。实现了基于快速傅立叶变换算法的高效耦合水平集流体体积求解器，以同时实现高分辨率和快速计算。在对应于 5.4% 气体体积分数的湍流通道流中产生多达 384 个气泡。由于向下的流动方向，气泡聚集在通道中心。气泡在通道中心引起额外的伪湍流，并且还能够通过减少剪切产生来衰减边界层中的能量。湍流动能收支表明通道中心产生了显着的浮力。除了边界层中的剪切产生峰值外，这里还观察到浮力产生和消散之间的局部平衡。比较局部产生和消散表明壁附近的边界层湍流和通道中心的气泡引起的伪湍流并存。液相和气相通过复杂的液-气界面耦合。局部流动拓扑分析在气泡周围的液相以及气相中进行描述。液相和气相的流动拓扑结构彼此显着不同。在气泡界面附近的液相中，局部耗散更占主导地位，而在气相中则优选局部内耗。在液相中，高耗散事件优选靠近界面，