A Question Regarding ABL Precursor Simulation

[yzl429]

Dear Xcompact3d developers,
I want to use xcompact3d to reproduce the ABL scenario described in a paper. The author states that xcompact3d was used for the precursor simulation of the ABL, with the friction velocity set to 0.442 m/s, the boundary layer height to 504 m, and the roughness length z₀ to 0.05 m. I replicated these settings but found that the maximum turbulent intensity in my processed data only reached 5%, failing to match the conditions reported in the paper. The paper indicates a turbulent intensity of 8% at y=90m. Where should I modify the input.i3d file? Currently, init_noise is set to 0.5—should I increase this value? The attachment contains the turbulence figure from the paper, along with the turbulence figure I obtained.
I look forward to your response. Thank you.

[KPerkins07]

Hello @yzl429,

I have also had the same issue trying to represent the paper results with turbulence being significantly below the expected range. I am finding that my ustar is decaying over the course of the simulation and little to no turbulence is being picked up towards the end.

I am trying to understand what could be causing the differences in the results as I am getting a very similar velocity profile representation and was wondering if you could share some details of your simulation setup? Specifically your grid configuration, ABL parameters and Runtime/statistic collection.

I am currently using a coarser mesh of 201,63,77 with init_noise also at 0.5 and inflow noise of 0.1 but my TI is reaching 1-2% maximum and 1% at hub height. Your 5% result at surface suggests you may have a better course of action to creation of the turbulent structures.

Any insights would be very helpful and hopefully I can help troubleshoot the overall issue.

Thank you in advance!

[yzl429]

hi KPerkins07,
Increase the value of init_noise to get what you want, inflow_noise is used when reading the precursor simulation, it has nothing to do with here.