刚性壁面附近气泡和自由面的耦合效应研究

Study on the interaction between the bubble and free surface close to a rigid wall

  • 摘要: 为研究刚性壁面附近的气泡与自由面的耦合效应,使用边界元方法(BEM)建立了一套考虑气泡、刚性壁面和自由面的数值模型。专注于与垂直平面成30°角的刚性壁面附近的气泡和自由表面之间的耦合效应,从两个方面进行研究:首先,为了研究气泡位置的影响,定义了一个无量纲的距离参数γh,它表示初始气泡与自由面和刚性壁面相交的垂直平面之间的距离。对于大尺度的气泡,在气泡的坍塌阶段会形成两个液体射流,自由面的高度的变化取决于γhγh较小时,自由面的高度在刚性壁面上达到其峰值,而γh相对较大时,此峰值出现在气泡正上方。其次,模拟了不同的气泡尺度下气泡和自由面的行为,发现气泡尺度对自由面的影响主要反映在气泡正上方的自由面高度上。当气泡尺度的影响相对较大时,该高度在整个过程中持续变大,而当气泡尺度的影响相对较小时,该高度呈先增加然后减小的趋势。

     

    Abstract: A numerical model considering the bubble, rigid wall and free surface is established by using the boundary element method (BEM). We concentrate on the influence between a bubble and the free surface near a rigid wall with 30 degrees to the vertical plane. We conduct this study from two aspects. First, to study the effect of the bubble position, a dimensionless distance parameter is delimited: γh denoting the distance between the initial bubble and the vertical plane crossing with the free surface and the rigid wall. We find that for large-scale bubbles, two liquid jets form at the collapsing stage of the bubble, and a change in the height of the free surface is found to rely on γh. At small γh the free surface reaches its peak height on the rigid wall, while the peak occurs above the bubble at relatively large γh. Second, we simulate the behavior of the bubble and free surface under different bubble scales, and we find that the effect of bubble scale on the free surface is mainly reflected in the height of the free surface above the bubble; this height increases continuously when the effect of the bubble scale is relatively great, whereas increases first and then decreases when the effect of the bubble scale is relatively small.

     

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