摘要
Based on the analysis of the known quantitative observations and qualitative measurements in the near wall region of the flow over a smooth wall, the distribution of the skewness factor in the vertical direction has been discussed for the openchannel flow over a fully roughened wall. It is found that when H/ks > 1. 0,S >0 is obtained in the range of y/H <0. 2, which means that there exist the low speed streaks, i. e. the turbulence of the now is produced by the phenomenon called 'burst'. For H/ks <1. 0, which belongs to the large-scale roughness case, the turbulence will be produced in another way. Moreover, the burst period is also discussed in this paper.
Based on the analysis of the known quantitative observations and qualitative measurements in the near wall region of the flow over a smooth wall, the distribution of the skewness factor in the vertical direction has been discussed for the openchannel flow over a fully roughened wall. It is found that when H/ks > 1. 0,S >0 is obtained in the range of y/H <0. 2, which means that there exist the low speed streaks, i. e. the turbulence of the now is produced by the phenomenon called 'burst'. For H/ks <1. 0, which belongs to the large-scale roughness case, the turbulence will be produced in another way. Moreover, the burst period is also discussed in this paper.
