Mechanics of Fluids - Topic 2 - Example 6 - Viscosity - Rotating Cone in Annulus

[@EulerCauchyNewtonGauss]

best teacher

[@SauravKumar-ex2bv]

Thank you sir.I had a doubt as to which direction to take gradient. In this case we could take the gradient in horizontal or vertical direction but we took perpendicular to the two surfaces. What is the reason behind it?

[@MohdZamriYusoff]

I am not sure what you are referring to. If you are referring to torque. Torque is F x perpendicular distance from axis of rotation. And F is viscosity x velocity gradient.

[@SauravKumar-ex2bv]

@@MohdZamriYusoff Sir , I was referring to the direction you took the velocity gradient,here it was normal to the two conical surfaces. I think that probably the direction to take the gradient in shear strain rate calculation should be normal to the fixed boundary. Please comment on this assumption.

[@MohdZamriYusoff]

The direction of velocity will be tangential to the surface. This will give shear stress and hence shear force in the same direction. This allow use to use radius directly when calculating torque since it is perperdicular to the force.

[@js_fx.007]

If cone is exchanged to hemisphere, what would be the solution? Plz help sir

[@MohdZamriYusoff]

Pls kindly check my other videos in Topic 2

[@serinavidyanarsing-wb8vb]

Thank you sir

[@D_iv_ya]

Thank you😇