Which of these phenomena results in viscous dissipation?

Acceleration of flow

Kinetic energy transformed into internal energy

Temperature gradient

Hot wall and cold wall case

Correct Answer : Kinetic energy transformed into internal energy

Explanation : The flow has kinetic energy which is partially dissipated in the form of internal energy due to the presence of skin friction drag that exists between the fluid and the flat plate. The change in internal energy leads to change in dissipation. These particular phenomena are known as viscous dissipation.

Recently Updated in Aerodynamics Questions

Which of these laws is used to find the heat flux at a point in the fluid?

Fourier law

Fick�s law

Kepler�s law

Newton�s law

Correct Answer : Option (A) : Fourier law

Explanation : Fourier law which is also known as the law of heat conduction is used to find out the heat flux at any point in the fluid. It is given by the formula:

Where, heat flux is in the y – direction
Minus sign indicates that the heat flows from high temperature to low temperature and thus q?_y is in opposite direction to the temperature gradient.

What happens to the shear stress if the thickness between the two plates is increased in a Couette flow?

Increases

Decreases

Remains same

Becomes infinite

Correct Answer : Option (B) : Decreases

Which of these laws is obeyed by a Newtonian fluid?

Prandtl law

Newtonian law

Shear stress law

Incompressible fluid law

Correct Answer : Option (C) : Shear stress law

Explanation : Newtonian fluids are characterized by those fluids that obey the shear stress law. Aeronautics domain makes use of newtonian fluids only (air, other gases). Those fluids that don’t obey shear stress law are known as non – newtonian fluids (blood).