Comment on: “Stokes’ first problem for heated flat plate with Atangana–Baleanu fractional derivative” [Chaos Solitons Fractals 117 (2018) 68]

In the sense of distributions, derivative Heaviside unit step function $H(t)$ is a generalized Dirac-$\delta$ distribution. If velocity $V(t)$ flat plate impulsive, as $V(t)=H(t)$ (i.e., it suddenly set into motion with at $t=0^+$), then its acceleration $V'(t)=\delta(t)$. The distribution has no point values. However, when forcing term an ODE (in $t$), contributes to solution. recently published paper [Chaos Solitons Fractals 117 (2018) 68] incorrectly treats being identically 0. This Comment analyzes source this error, and provides guidance on how correct (based established literature). mathematical error identified in addition some issues about rheological models fractional derivatives, which are also noted. That say, whether or not "Atangana--Baleanu derivative" used 68], solution Stokes' first problem provided therein correct.