边墩纵向宽度对回流长度的影响研究

Relationship between abutment dimension and the downstream recirculation length

采用试验和三维紊流模型相结合,对长方体边墩在不同纵向宽度条件下的回流长度变化规律进行了研究。三维模型采用大系数法与壁函数法相结合对边墩区域边界进行了处理。研究结果表明:在模拟条件下,边墩后的回流长度随着边墩宽长比的增大而减小,在边墩宽长比较小时,边墩的宽长比对边墩后回流长度的影响较为敏感;当边墩宽长比大于4左右后,回流长度变化较小,此时已相当于河道的突扩问题。以边墩宽长比为0.02(丁坝)时的回流长度L0为基准,利用实测资料建立了不同边墩宽长比条件下的回流长度计算公式。

The relationship between the longitudinal dimension of an abutment and the recireulation length behind it is established based on the experimental data and the numerical results using a 3D model. The law of wall and the large coefficient method are used in the 3D model. The results show that the length of recirculation decreases with rise in the ratio of longitudinal dimension （b） to lateral dimension （D）. The recirculation length is sensitive to changes in b/D when b/D is small, and becomes a constant when b/D is larger than 4, at which the results are equivalent to the solutions to sudden expansion problems. A formula is proposed to calculate the length of recirculation for longitudinal dimension of an abutment.