hydrodynamics is the study of fluids in motion. Your question needs to be reworded to make more sense.
Rod bearing (short for connecting rod bearing) Is the bearing where the connecting rod is attached to the rotating crankshaft.
When rod bearing clearance is too tight the end result is what is called a spun bearing -- definitely a bad thing. Bearing clearance is the difference between the inside diameter of the bearing and the outside diameter of the crankshaft journal to which it is clamped. The bearing is supplied pressurized oil fed by the oil pump, it should never touch the crankshaft journal but should always float on a wedge of oil. If the clearance is too tight the bearing touches or drags on the crankshaft journal and the journal grabs the bearing and spins it inside the housing into which it is clamped -- which in the case of a rod bearing is the big end of the connecting rod. Once this happens it all pretty much self destructs as it chews up the big end of the connecting rod and the crankshaft journal as well.
bearing journal
Connecting rod journals are the part of the crankshaft where the connecting rods attach to. There is one rod journal for each piston/connecting rod in the engine. These journals have a machined surface so the connecting rod bearings can move smoothly as the crankshaft rotates.
bearing journal
I know that the stock connecting rod journal diameter is 2.123"
A main bearing gives the crankshaft a smooth surface to spin on, and a rod bearing, provides a surface for the connecting rod to rotate on.
The connecting rod journal is also commonly referred to as the "big end" of the connecting rod. It is the part of the connecting rod that connects to the crankshaft, allowing for the conversion of linear motion of the piston into rotational motion. This component is critical for the engine's operation, as it facilitates the transfer of power generated during combustion.
If the bearing has not spun or seized, you drop the oil pan, take the rod cap off of the rod and put the new bearing in. The bearing is in two pieces, half in the rod and half in the rod cap. If the bearing has spun, you should remove the crankshaft and either have the rod journal polished or machined for a thicker bearing.
There isnt any
The connecting rod journal is also called the crankpin. It is the part of the connecting rod that rotates around the crankshaft, connecting the piston to the crankshaft and converting linear motion into rotational motion. The crankpin allows for the movement of the piston as the engine cycles through its power strokes.
If it is a connecting rod or bearing--be prepared to put in a new motor