# The net force of an ideal flow - Fluid Mechanics

Q.  The net force of an ideal flow is equal to the sum of nonzero values of
- Published on 04 Aug 15

a. pressure force and gravity force
b. viscous force and gravity force
c. pressure force and viscous force
d. pressure force, viscous force and compressibility force

ANSWER: pressure force and gravity force

#### Discussion

• Pankaj   -Posted on 28 Sep 15
While considering fluid dynamics, various forces act on fluid such as gravity force, pressure force, viscous force, turbulent force and compressibility force. Therefore net force acting on the fluid is the sum of all these forces.

Net force = Fg + Fp + Fv + Ft + Fc

As the compressibility of fluid id negligible, its force can be neglected.

∴ Net force = Fg + Fp + Fv + Ft

This equation is called as Reynold's equation of motion.

If compressibility and turbulence effects on the fluid are neglected then,

Net force = Fg + Fp + Fv

This equation is called as Navier-stockes equation of motion. It is useful in the study of viscous flow.

If the fluid flow is considered as an ideal flow then, the effect of viscous force can also be neglected. Ideal fluid does not have viscosity.

∴ Net force = Fg + Fp

This equation is called as Euler's equation of motion. Therefore, net force of an ideal flow is equal to the sum of nonzero values of gravity force and pressure force.

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