“…The scalar dissipation rate is a measure of the rate at which a scalar quantity is mixed and dispersed in a fluid flow. In other words, it represents the rate at which the scalar field is diffused and smoothed out by the turbulence in the flow (Bao et al., 2023; Wandel, 2023). These frequency distributions reveal that the Forchheimer regime is generally characterized by more locations where non‐zero local concentration gradients can be found than the Darcy‐ flow regime, even as there is a considerable number of occurrences of very small gradient values (see, e.g., Figure 9d).…”