Question

is there any formula for viscosity and what is the formula for viscous drag force

Answer 1

Hello!

The drag force (F) experienced by a body in a fluid is given by the Stoke's Law, whicb is

F = 6πηrv

where

η is the viscosity of the fluid

r is the radius of the body (considering it as a sphere)

v is the velocity of the body

The viscous force (f) exerted by a fluid if given as

f = ηA(dv/dx)

where A is the surface area of contact

and dv/dx is the velocity gradient