Kinematic viscosity and dynamic viscosity are related, but they belong to two different concepts, but it is easy to confuse the concepts of kinematic viscosity and dynamic viscosity.
Viscosity refers to the internal friction of a liquid, indicating the amount of resistance between molecules.
Kinematic viscosity is the ratio of the viscosity of a fluid to the density of that fluid at the same temperature. It is a measure of the flow resistance of a fluid under the action of gravity, and the unit of kinematic viscosity is (m^2)/s. Kinematic viscosity ν=μ/ρ, μ is the dynamic viscosity of the liquid, ρ is the density of the liquid.
Dynamic viscosity refers to the force required to produce a unit flow rate using a unit area of liquid layer per unit distance. In the unit system, the unit of kinematic viscosity is pa.s. The formula for calculating the dynamic viscosity of the liquid: μ=τ/(du/dy), where τ is the internal frictional resistance per unit area of the liquid flow, and du/dy is the velocity gradient.
Kinematic viscosity and dynamic viscosity are two indicators for evaluating the viscosity of lubricating oil. The smaller the dynamic viscosity, the better the low temperature fluidity; on the contrary, the worse the low temperature fluidity of the lubricating oil. The smaller the kinematic viscosity, the lower the lubricating oil viscosity, the greater the kinematic viscosity, the higher the lubricating oil viscosity.