  Deep Learning (DL) algorithms are becoming increasingly popular for the
reconstruction of high-resolution turbulent flows (aka super-resolution).
However, current DL approaches perform spatially uniform super-resolution - a
key performance limiter for scalability of DL-based surrogates for
Computational Fluid Dynamics (CFD).
  To address the above challenge, we introduce NUNet, a deep learning-based
adaptive mesh refinement (AMR) framework for non-uniform super-resolution of
turbulent flows. NUNet divides the input low-resolution flow field into
patches, scores each patch, and predicts their target resolution. As a result,
it outputs a spatially non-uniform flow field, adaptively refining regions of
the fluid domain to achieve the target accuracy. We train NUNet with
Reynolds-Averaged Navier-Stokes (RANS) solutions from three different canonical
flows, namely turbulent channel flow, flat plate, and flow around ellipses.
NUNet shows remarkable discerning properties, refining areas with complex flow
features, such as near-wall domains and the wake region in flow around solid
bodies, while leaving areas with smooth variations (such as the freestream) in
the low-precision range. Hence, NUNet demonstrates an excellent qualitative and
quantitative alignment with the traditional OpenFOAM AMR solver. Moreover, it
reaches the same convergence guarantees as the AMR solver while accelerating it
by 3.2-5.5x, including unseen-during-training geometries and boundary
conditions, demonstrating its generalization capacities. Due to NUNet's ability
to super-resolve only regions of interest, it predicts the same target
1024x1024 spatial resolution 7-28.5x faster than state-of-the-art DL methods
and reduces the memory usage by 4.4-7.65x, showcasing improved scalability.
