Hi Juan Diego, Indeed, we describe in our paper the trip forcing. The tripping has a temporal part (third-order Lagrange interpolants with specific time scale) and a spatial part (the h^i(z)). We typically use white noise for these h(z), low-pass filtered with a spectral cutoff filter at a wavenumber 2pi/z_s. So what one gets in h(z) is just random sines and cosines up to a spanwise scale z_s. The implementation of course needs to make sure i) that you have the same random numbers for the whole spanwise extent, and ii) that when restarting a simulation you continue the previous tripping in a smooth way as to not generate any peaks (discontinuities) at the restart. Please let me know if you have further questions, and I am happy to help more. Best regards, Philipp Schlatter On 2018-02-23 18:29, [email protected] wrote:

Dear all,

I've seen several papers using Nek5000 with a tripping mechanism based on a forcing term, explained in a paper by Schlatter & �rl� (2012). However, they talk about using random harmonic signals h^{i}(z). My question is: What is the shape of such signals and how do you make them random?

Thanks,

Juan Diego

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