Hi, I have some basic questions regarding 1)What is the difference between acoustic spectrum and turbulent spectrum 2)Let us say you do an LES calculation where the problems is unsteady do you check whether turbulent spectrum satisfy the -5/3 condition. Can you please give me some reference. Regards Pratap

For your question (2) you should say the -5/3 conjecture since it would only be a condition if actually held true.

For (1) the acoustic spectrum is the energy distribution as a function of the sound frequency while the turbulence spectrum is the distribution of energy as a function of the wavenumber. Ones in time and the others in space.

So according to you everybody check whether -5/3 is holding true or not at each time (from t=0 to t=100). So initial condition of LES is generated in keeping mind that initial condition should satisfy -5/3 spectrum. you said that acoustic spectrum is the energy distribution of the sound frequency that means integrated energy of the domain or energy of some point. Z