One of the most controversial topics in the field of convection in porous media is the issue of macroscopic turbulence. It remains unclear whether it can occur in porous media. It is difficult to carry out velocity measurements within porous media, as they are typically optically opaque. At the same time, it is now possible to conduct a definitive direct numerical simulation (DNS) study of this phenomenon. We examine the processes that take place in porous media at large Reynolds numbers, attempting to accurately describe them and analyze whether they can be labeled as true turbulence. In contrast to existing work on turbulence in porous media, which relies on certain turbulence models, DNS allows one to understand the phenomenon in all its complexity by directly resolving all the scales of motion.
Our results suggest that the size of the pores determines the maximum size of the turbulent eddies. If the size of turbulent eddies cannot exceed the size of the pores, then turbulent phenomena in porous media differ from turbulence in clear fluids. Indeed, this size limitation must have an impact on the energy cascade, for in clear fluids the turbulent kinetic energy is predominantly contained within large eddies.
Special Issue: Fluid Flow in Fractured Porous Media
