  A model for the Reynolds number dependence of the dimensionless dissipation
rate $C_{\varepsilon}$ was derived from the dimensionless
K\'{a}rm\'{a}n-Howarth equation, resulting in $C_{\varepsilon}=C_{\varepsilon,
\infty} + C/R_L + O(1/R_L^2)$, where $R_L$ is the integral scale Reynolds
number. The coefficients $C$ and $C_{\varepsilon,\infty}$ arise from asymptotic
expansions of the dimensionless second- and third-order structure functions.
This theoretical work was supplemented by direct numerical simulations (DNSs)
of forced isotropic turbulence for integral scale Reynolds numbers up to
$R_L=5875$ ($R_\lambda=435$), which were used to establish that the decay of
dimensionless dissipation with increasing Reynolds number took the form of a
power law $R_L^n$ with exponent value $n = -1.000\pm 0.009$, and that this
decay of $C_{\varepsilon}$ was actually due to the increase in the Taylor
surrogate $U^3/L$. The model equation was fitted to data from the DNS which
resulted in the value $C=18.9\pm 1.3$ and in an asymptotic value for
$C_\varepsilon$ in the infinite Reynolds number limit of
$C_{\varepsilon,\infty} = 0.468 \pm 0.006$.
