  Two well-known turbulence models that describe the energy spectrum in the
inertial and dissipative ranges simultaneously are by Pao~(1965) and
Pope~(2000). In this paper, we compute the energy spectrum $E(k)$ and energy
flux $\Pi(k)$ using direct numerical simulations on grids up to $4096^3$, and
show consistency between the numerical results and the predictions by the
aforementioned models. We also construct a model for laminar flows that
predicts $E(k)\sim k^{-1} \exp(-k)$ and $\Pi(k)\sim k \exp(-k)$. Our model
predictions match with the numerical results. We emphasize differences on the
energy transfers in the two flows---they are {\em local} in the turbulent
flows, and {\em nonlocal} in laminar flows.
