This may be a trivial point, perhaps it's a lack of understanding on my part? When I was first introduced to fluid mechanics I was instructed to write the continuity and (generalized) Navier-Stokes equations as such
$$\boldsymbol{\nabla}\boldsymbol{\cdot}\boldsymbol{u}=0,$$
$$\rho\left(\frac{\partial}{\partial t}+\boldsymbol{u}\boldsymbol{\cdot}\boldsymbol{\nabla}\right)\boldsymbol{u}=-\nabla p +\boldsymbol{\nabla}\boldsymbol{\cdot}\boldsymbol{\tau},$$
where the nabla operator in front of the pressure term is not a 'boldsymbol' operator since the fluid pressure is a scalar. However, in the literature this doesn't seem to be the general consensus. More often I find that these equations are expressed as
$$\nabla\cdot\boldsymbol{u}=0,$$
$$\rho\left(\frac{\partial}{\partial t}+\boldsymbol{u}\cdot\nabla\right)\boldsymbol{u}=-\nabla p +\nabla\cdot\boldsymbol{\tau},$$
where the neither the nabla or dot operators have the 'boldsymbol' typeface.
Just looking for some clarification really.
Thanks!