For which of these conditions was Newtonian law devised?

Force on flat plate in subsonic flow

Force on curved airfoil in moving fluid

Force on a flat plate in hypersonic flow

Force on inclined plane in moving fluid

Correct Answer : Force on inclined plane in moving fluid

Explanation : Isaac Newton worked on a fluid – dynamics theory which would address the force on an inclined plane in a moving fluid applicable to low – speed flow which was later applied to hypersonic flow. According to the law, the force varies as square of sine of the deflection angle.

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).