Yes Leo, a blue filter can sometimes enhance fog. You may also find that a polarizer turned the 'wrong' way may also enhance fog for you. You might also try ortho film. It really depends a lot on the scene, the light, the direction of the light etc.
The best way to get good fog, though, is timing... if you understand dew point then you're probably going to know exactly when to be in the right spot and what angle to shoot from. My attempts with various filters never delivered results as dramatic as getting out of bed early and applying some patience
By the way, I suspect that primary mechanism for scattering from ground fog and haze is Mie scattering, in which the size of the water droplets has a correspondence to the wavelength scattered. The droplets are quite random in size and hence all wavelengths are quite equally scattered, producing whitish scattered light. Quite often people speak of Rayleigh scattering and its 1/wavelength^4 dependence, which suggests
much stronger scattering from shorter (bluer) wavelengths than IR, but my feeling is that Mie normally plays the larger role with ground fog. A point of confusion is that there are two scattering regions one must consider. There is (1) scattering in the upper atmosphere between your subject and the sun, and (2) scattering between yourself and your subject. I think Rayleigh applies mostly to (1) and Mie to (2). I haven't put much thought into it though, honestly.