Variation of absolute viscosities with fluid temperatureĪbsolute liquid and vapor viscosities are strong functions of liquid temperatures. Two of the main parameters associated with fluid dynamics are a fluids viscosity, which characterizes its resistance to flow and surface tension, which is the. Hence kinematic viscosity of a fluid is also dependent only in the state of the fluid and not the flowrate. It should be noted that absolute viscosity (µ) and density (ρ) are both fluid properties dependent only of the state of the fluid (pressure and temperature). This ratio is known as kinematic viscosity (ν) of a fluid. Hence the ratio of viscous forces to inertial forces in the fluid is represented by (absolute viscosity / density). Viscous forces are represented by a density of the fluid and viscous forces are represented by the absolute or dynamic viscosity of the fluid. In some cases the ratio of viscous forces and inertial forces in a fluid flow is considered to be important. Unit of viscous stress are same as units of pressure.
Newton's law stands for viscous force per unit area of the fluid, which is represented by viscous stress. Here, the negative sign indicates direction opposite to the fluid flow and µ is the absolute viscosity or dynamic viscosity of the fluid which acts as a proportionality constant. Velocity Gradient = dV/dy ≈ ΔV/Δy (as Δy→0)
0 kommentar(er)
