Viscous force
- When a fluid is exposed to tangential force on its surface, viscous force provides resistance (internal) force (shear).
- When a flow passes across such a surface, the molecules in the flow that gets close to the surface stick to it. As a result, the relative velocity of the fluid around the surface is 0. To put it another way, the fluid molecules are just overcome at the same speed as the surface.
- When a fluid slips or tends to slip on the neighboring layer in contact in a constant flowing fluid, the two layers provide tangential force to one another in order to reduce relative motion.
- Viscosity refers to a material's ability to resist displacement between its layers. Also known as viscous force, it is the force that opposes relative motion between the layers.
- Viscous force can be given as:
here,
- Force
- the fluid's viscosity
-each plate's area
-shear deformation rate