Friction Between Liquid and Solid Surface How does friction between liquid surface and solid surface differ from viscosity, the friction between liquid and liquid surfaces? Also has a word describing the process been invented or is liquid-solid friction suffice? Any ideas are appreciated, I'm looking for various perspectives.
 A: Tribology (not the study of tribes!) is the study of what happens when things 'rub'. This involves friction and wear when solids rub against other solids (such as in mechanical bearings) and the effect of liquids (such as 'lubricants') and other fluids.
Friction at a solid-liquid interface is still called friction. It is a 'damping' or 'dissipative' force, in part due to the viscosity of the liquid (internal friction), but also subject to other (external) factors such as the 'roughness' of the solid surface.
Whereas the friction between two solids is typically described as 'static' and 'kinetic' friction with the 'roughness' of each surface being proportional to the co-efficient of friction (both static and kinetic), the presence of a liquid on the surface changes the friction by introducing fluid dynamics. Static friction is no longer present and the kinetic friction is now affected not only by the surface roughness but also by the properties of the liquid, including viscosity.
A liquid flowing along the surface of a solid will experience a shear stress at the surface due to it's roughness. As the solution of the governing fluid mechanics equations involves knowing the boundary conditions, in most cases, the velocity of the liquid at the solid surface is given as zero, known as the 'no-slip' condition.
In some cases, a liquids may exhibit very low viscosity near the solid surface, such that, it may have some (non-zero) velocity relative to surface of the solid, which is known as 'slip'.
In this case, the velocity profile of the liquid relative to the solid is shown below.

The extrapolated distance within the solid surface where the tangential velocity component of the liquid would otherwise vanish is called the Navier slip length, $L_s$. 
This slip length is affected by (amongst other things), weak liquid-solid attraction, surface roughness, high shear rates and nucleation of nanobubbles at hydrophobic surfaces.
On a conceptual level, a deep understanding of friction, from atomic through to macroscopic level, is quite complex and involves looking at the interaction of electrons (eg: van der Waals bonds in liquids) and how energy is propagated through an 'atomic lattice'. The vibration of atoms (or ions) bound together can be described through a notion of quantum 'quasiparticles' known as 'phonons'. Friction occurs when things 'rub' together because energy is transferred at the surface by the interaction of electrons and phonons, as observed through the effect of sound (low frequency phonons) and heat (higher frequency phonons).
A: The friction between a solid and liquid is a function of viscosity.
The best way to answer this is with a model setup called Couette flow where a fluid sandwiched between two plates is sped up by the movement of the top plate:


Image source: University of Virginia, Physics 152 taught by Michael Fowler

The friction force $F$ that the fluid exerts on the plate (opposing its motion) is given by the simple equation found here and reproduced below:
$F = \mu A\frac{u}{y}$
$\mu = shear\ viscosity\ of\ fluid$ 
$A = area\ of\ top\ plate$ 
$u = speed\ of\ top\ plate\ (v_o\ in\ the\ diagram\ above)$ 
$y = separation\ of\ the\ two\ plates\ (d\ in\ the\ diagram\ above)$ 
