[Cathar]

Originally Posted by bobo5195

I think that you might be wrong there. A thermal boundary layer (thin layer of liquid above the surface) , is where conduction is the dominant transfer medium in the fluid. Conduction does occur in fluids but it only dominates over small distances such as the exit of the jets on the storm seris of blocks. What your effectively saying is that the prandtl number is infinite, whihc is not the case.

No, now you're being nit-picky in the extreme, and taking the discussion into a topic of philosophical classification.

Of course I'm aware of the static layer/film of water molecules that are in contact with the metal's surface and that the primary means of heat transfer from the metal into those molecules is conduction. Never meant to imply that the Prandtl number is infinite.

The issue is how thick is that layer of static conduction? The thickness of the pure-conduction layer is directly affected by the motion of the water. Since the conduction layer is made of a liquid and is affected by means of liquid motion, then it merely becomes part of the overall definition of convection.

We can get philosphical about it if you want. Convection is a thin layer of conduction through a liquid at a thermal boundary followed by heat transfer through means of motion. Given that the thermal boundary layer is affected by fluid motion it is therefore no longer an invariable static body of mass and thus this action collectively falls under the umbrella definition of the "convection process". If you want to argue that the convection process involves some amount of conduction, fair enough, but the whole process is not purely conduction because of the variable nature of the conduction layer.

My estimation is that the exit to the storm is all thermal boundary layer. If it is not boundary layer then it should be by design as by definition the boundary layer is where most of the special luvly heat transfer takes place, or at least the major part of the thermal gradient.

Perhaps we're just quibbling over clarification of terms. You're basically saying that as close to all molecules of water entering as possible are actively involved in the thermal transfer process (what I call convection, what you're calling conduction but that which I believe still falls in the term convection), and yes, I agree with you. That is the singular driving thought paradigm behind all my block designs => "How can I make ALL of the water molecules become directly involved in the transfer of heat from the metal into the liquid".

Of course, that's exactly what micro-channels try to do by literally forcing/constraining all water molecules to act within the thermal boundary layer, but all true micro-channel implementations have tremendous issues with pressure-drop management as well as cloggage (<0.1mm channels clog very easily despite best efforts), and those are the additional knurs that can't be dismissed for enthusiast watercooling use.

Conduction is heat transfer in a stationary medium; not nescessarly a solid.

Indeed. Look up though. At no point did I say that conduction had to be through a solid. I said conduction occurs through a static (immobile) body of mass. This means that "mass" that can be a liquid, gas or solid, which is the same thing you said just above, just worded differently.

I appreciate that you're just trying to flex the theoretical muscle and classify what's going on. I'm just using commonly used terms of thermal transfer performance as a handy means of performance measurement/classification. If you want to argue that it's pure conduction then that's somewhat outside the general broad level discussion that we're trying to achieve here.