A recent magnetic resonance imaging (MRI) study (Boyce et al., Phys. Rev. Fluids, 2019, 034303) found that when two bubbles were injected side-by-side into an incipiently fluidized bed, below a critical injection volume, one bubble collapsed, while the other bubble survived, reaching the bed surface. Limitations in the experimental measurements left open questions about the apparent collapse: (1) did the bubble actually collapse or rather move out of the imaging plane and (2) if the bubble collapsed, was it due to gas transfer between bubbles or a preference for gas to channel toward the surviving bubble. Here, we demonstrate that computational fluid dynamics - discrete element method (CFD-DEM) simulations can recreate this phenomenon. Simulation results reveal that the bubble does in fact collapse and that this collapse occurs because the slight size difference between the two bubbles causes gas flow to channel preferentially to the larger bubble, leaving the smaller bubble without enough gas flow to support its roof.

中文翻译：

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CFD-DEM研究：将一个气泡与另一个气泡并排注入流化床中而崩溃

最近的磁共振成像（MRI）研究（Boyce等人，Phys.Rev.Fluids，2019，034303）发现，当两个气泡并排注入临界流以下的初始流化床中时，一个气泡破裂，而另一个气泡幸存下来，到达床表面。实验测量的局限性使人们对表观坍塌问题悬而未决：（1）气泡是否确实塌陷，或者更确切地说是从成像平面移出；（2）气泡是否塌陷，是由于气泡之间的气体转移还是对气泡的偏好所致？气体流向尚存的泡沫。在这里，我们证明了计算流体动力学-离散元方法（CFD-DEM）模拟可以重现这种现象。