Consider a flow through two parallel plates with infinite length. Then according to Newtonian inner friction law, shear stress at the connection of fluid to one late will be related to dynamic viscoisity and velocity gradient of fluid. So does that mean that whatever the material of plate is, shear stress will not change?
Thank you Mr.Chandel. I know it will change in practice but how to explain the Newtonian law? I have one idea that the Newtonian law can only be used for Newtonian fluid which is rarely found on earth. We can take ideal gas as an analogy for Newtonian fluid. It's hard to find ideal gas but we can assume one. So in a more actual way, we will use some empirical equations to calculate the real shear stress. For example the Fanning friction law. I don't know whether my idea is right or wrong.
Newton's law should be valid for a Newtonian fluid no matter what is the material of the wall. However when we imposing no-slip boundary condition, we indirectly imposing the shear stress. If the wall material is such that it deforms due to the fluid shear then the no-slip condition is not valid and we should use a boundary condition of equal shear stresses in the fluid and the solid. Then the wall material properties will have an impcat.
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