Turbulence model to run Turbsim

Hi, I’m going to use “USRINP” as Turbulence model to run Turbsim, which means I have to customize some wind spectrum. But I find it hard to figure out how to get the Kaimal spectrum as shown below(formula 1) , I have read some articles, most of which describe wind spectras in the form of Formula 2, but in order to follow the Turbsim or IEC instructions, I have to try to convert them into the form of Formula 1. So could you please provide a general explanation of how you converted Formula 2 into Formula 1? I need a hint from you to proceed with my subsequent work
图片1

图片2

Dear @HaiYan.Liao,

I’m not sure I really understand your question. The two formulas you shared appear to be very similar, with the 2nd formula tied to u (not k = u, v, or w in the first formula) and given for specific values L_u and V_hub.

Moreover, when using TurbModel = “USRINP” in TurbSim, you can define the wind spectrum however you want (independent of the Kaimal spectrum if you desire).

Best regards,