During the derivation of the Euler (momentum) equation, three forces were acting on the volume: a pressure force, a gravity force, and a friction force.

Question

Which force or forces is/were neglected during this derivation? (Multiple answers can be correct)

The force due to pressure

The friction force

The gravity force

Answer 1

In the derivation of the Euler (momentum) equation, typically, the following forces are considered:

1. Pressure Force: This is a significant force and is included in the momentum equation as it relates to how pressure varies throughout the fluid.

2. Gravity Force: This is also included in the momentum equation, as it accounts for the effect of gravity acting on the fluid.

3. Friction Force: The friction force (viscous forces) is often neglected in the derivation of the Euler equation because the Euler equation is derived under the assumption of inviscid flow (i.e., flow that is non-viscous).

Therefore, the force or forces that are neglected during the derivation of the Euler (momentum) equation include:

• The friction force.

So, the relevant answer is:

• The friction force (is neglected).