turbulent flows in pipe

steven

Thanks in advance for any reply.

I am trying to do turbulence simulation test in a long pipe (say D=0.1m, L=1m). Then I put say 12m/s airflow velocity in inlet. Then I choose k-W model and select 5% turbulence intensity. Other parameters are in default. I have very good quality mesh with highly dense near wall grids. However, the turbulence kinetic energy just disspates very quickly from inlet (like from 1.0 at inlet to 1E-5 at outlet). But I thought I should have increased k along the pipe. Where did I do wrong or any explanations?

Thanks a lot!