In this paper, we establish novel higher-order commutator estimates for the pressureHessian associated with three-dimensional incompressible fluid flows. By employing a localizedLittlewood-Paley decomposition and utilizing the classic Calder´on-Zygmund framework, weprove sharp bounds for the commutator RiRj, u · ∇ in fractional Sobolev spaces Hˢ (R3) fors > 5/2. These estimates provide an intrinsic geometric control over the localized oscillations ofthe pressure field without enforcing structural smallness assumptions on the velocity field.
Efe SARICI (Mon,) studied this question.