Determine the required stochastic-model parameters from physical flow inputs
Determine rigorous estimates of the Taylor microscale \(\lambda_{T}\), aerodynamic roughness length \(z_{0}\), friction velocity \(u_{\tau}\), and boundary-layer thickness \(\delta\) from the given surface geometry and undisturbed flow velocity, rather than relying on scaling relationships and reasonable guesses.
References
The required modeling parameters \lambda_{T}, z_{0}, u_{\tau}, \delta are not known a priori. Scaling and empirical relationships exist to place reasonable guesses, e.g., elaborating on \lambda_{T}=(15\nu\overline{u{\prime 2}/\epsilon){1/2}, but rigorous estimates based on given surface geometry and undisturbed flow velocity are not strictly possible.
— A stochastic modeling framework to generate 2-D rough-wall high-Reynolds-number turbulent boundary layers
(2609.10236 - Ehsani et al., 9 Sep 2026) in Section 6, “Limitations,” item 1