Which modeling technique struggles to concurrently scale both mechanical and thermally induced turbulence?

The wind tunnel method is primarily used for experimental testing of fluid flow, and while it can effectively simulate airflow and the behavior of particles or contaminants within that flow, it has limitations when it comes to accurately scaling both mechanical turbulence (caused by factors such as obstacles and shear layers) and thermal turbulence (caused by temperature differences in the fluid).

In a wind tunnel, the conditions are typically highly controlled and may not represent the vast range of turbulence scales present in the real atmosphere, especially when dealing with varying thermal conditions. This can result in discrepancies between model predictions and actual atmospheric behavior, particularly in complex scenarios where both mechanical and thermal turbulence significantly influence dispersion.

On the other hand, techniques like Computational Fluid Dynamics (CFD) offer more flexibility in simulating both types of turbulence by using numerical methods to solve the governing equations of fluid motion. The Gaussian Dispersion Model, though limited to certain assumptions, also effectively handles dispersion scenarios under specific conditions. Puff modeling is designed for handling time-dependent releases and can incorporate varying turbulence conditions to some extent.

Thus, the wind tunnel method is identified as the technique that struggles to effectively and accurately scale both mechanical and thermally induced turbulence.