Dynamic viscosity and kinematic viscosity are two different expressions of fluid viscosity, and there are both differences and connections between them.
Kinematic viscosity mainly describes the flow performance of a fluid through a specific capillary under the action of gravity. Specifically, at a stable temperature, the time required to measure the flow of a certain volume of liquid through a calibrated glass capillary viscometer is the product of this time and the capillary constant of the viscometer, which is the kinematic viscosity of the liquid. This method is widely used for viscosity measurement of liquids, petroleum products, etc., and is a very practical and accurate technical means.
Dynamic viscosity focuses more on the internal friction force of the fluid itself, which is the resistance generated by relative motion between adjacent layers inside the fluid during flow. This resistance is related to factors such as fluid properties, temperature, and flow rate.
Although kinematic viscosity and dynamic viscosity have different expressions, they are both important parameters used to describe fluid viscosity. In practical applications, we can calculate the dynamic viscosity by measuring the kinematic viscosity, or calculate the kinematic viscosity based on the known dynamic viscosity. In this way, we can have a more comprehensive understanding of the flow performance of fluids, providing strong support for scientific research and technological applications in related fields.