ABSTRACT
In Chapter 4 we have seen classical solutions of the Navier–Stokes equations: the solution u → https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315373393/e1c1ff9e-5083-409e-83f8-9c892d4b410a/content/eq991.tif"/> was C 2 in space variable, and C 1 in time variable, and the pressure was C 1 in space variable, so that all the derivatives in the Navier–Stokes equations were classical derivatives. In Chapter 5, we considered measurable solutions of the integral equations derived from the Navier–Stokes equations, and we did not assume any differentiability on the solutions.
