Yield Point In Drilling Mud Formula, Factors & Application
https://www.youtube.com/watch?v=saN0RrdEIas

Yield Point in drilling mud is defined as the measure of the fluid’s initial flow resistance or the calculation of a value required to move the fluid in terms of shear stress. It can also be stated that the yield point is equivalent to the force of attraction between the particles of fluid colliding with one another.
https://www.drillingmanual.com/yield-point-drilling-mud/