Navier-Stokes is a set of non-linear differential equations, not a function. It's extremely hard to analytically solve the equation (unless you give it some ext

Navier-Stokes is a set of non-linear differential equations, not a function. It's extremely hard to analytically solve the equation (unless you give it some extremely simplifying constraints), so the best you can do is solve it discretely and iteratively. Then you're just looking at the neighborhood of a given point in space and time to compute the next value at that point, so it could really be any topology.