Question

What is viscous force?

Answer 1

Viscous force

1. When a fluid is exposed to tangential force on its surface, viscous force provides resistance (internal) force (shear).
2. 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.
3. 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.
4. 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.
5. Viscous force can be given as:

$F=\mu A\frac{u}{y}$

here,

$F$- Force
$\mu$- the fluid's viscosity
$A$-each plate's area
${\displaystyle \frac{u}{y}}$-shear deformation rate