The impact of boundary conditions on spectral condensation of turbulence: Experiments and numerics

Flow patterns that are coherent over the entire domain can emerge in 2D and anisotropic 3D turbulent flows. In a combined experimental and numerical study of flow in a quasi-2D electrolyte layer, we observe, for electromagnetic driving that is sufficiently strong, the emergence of well-ordered large scale patterns, whose structure strongly depends on boundary conditions. For rectangular lateral boundaries of high aspect ratio, the patterns exhibit a well-defined length scale that is comparable to the smaller lateral dimension. For periodic lateral boundaries, an array of jets are observed; by contrast, with no-slip lateral boundaries, a pattern of vortices are found. The patterns are found to persist, even with forcing that is spatially random. The spectral behavior of the patterns will be described in this talk.