圧力勾配のある乱流境界層における混合距離について (第2報)

抄録

1. Applying the von Karman's similarity theory to flow near the wall, the following analytical form of the mixture length is obtained. [numerical formula] n=0∼1, K=0.4, σ_1=8.4, C_2=-3.8. (See below as to notation.) This expression shows fairly good agreement for Nikuradse's divergent channel flow (1st Report) and may be recommended for use to the general turbulent boundary layer with proper consideration. 2. For flow in a convergent channel the analysis as for the divergent case (1st. Report) has been made, and it is shown that the mixture length distribution can be approximated by either the same formula for flow along flat plate (6') or Ky without much error. Discussion like 1. cannot be made because of the uncertainty of calculated results. 3. Lastly the remark is added that the approximation of shearing stress distribution by pressure gradient only, as usually used, is not satisfactory even in the sense of the first order and needs the correction due to acceleration terms. The idea of "effective pressure gradient" is presented.