  A new modeling approach for large-eddy simulation (LES) is obtained by
combining a `regularization principle' with an explicit filter and its
inversion. This regularization approach allows a systematic derivation of the
implied subgrid-model, which resolves the closure problem. The central role of
the filter in LES is fully restored, i.e., both the interpretation of LES
predictions in terms of direct simulation results as well as the corresponding
subgrid closure are specified by the filter. The regularization approach is
illustrated with `Leray-smoothing' of the nonlinear convective terms. In
turbulent mixing the new, implied subgrid model performs favorably compared to
the dynamic eddy-viscosity procedure. The model is robust at arbitrarily high
Reynolds numbers and correctly predicts self-similar turbulent flow
development.

Chaotic Dynamics