Momentum balance derivation in equations

In summary, the conversation discusses the application of fluid mechanics equations to different flow directions and the need for additional terms, such as the (ρgh) term, when considering gravity in vertical systems. It also mentions how gravity may be ignored in gas dynamics at certain scales, but is more relevant in liquid systems. Other body forces may also need to be taken into account in chemical engineering.
  • #1
Fishinev
2
0
I'm a little confused, in my fluid mechanics course we've covered many equations and they are all derived using an x-direction fluid flow. If I was to use these in a system in which fluid flowed in the y-direction would I have to re-derive them? Or would it be more of a case of using a horizontal system in a vertical direction?
 
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  • #2
Welcome to PF!

Hi Fishinev! Welcome to PF! :smile:
Fishinev said:
I'm a little confused, in my fluid mechanics course we've covered many equations and they are all derived using an x-direction fluid flow.

Do you mean that the entire flow is horizontal, so that gravity doesn't have to be taken into account?

In that case, if you want to apply the equations to a vertical system, you'll need extra (ρgh) terms to deal with gravity.
 
  • #3
In that case, if you want to apply the equations to a vertical system, you'll need extra (ρgh) terms to deal with gravity.

If this is a gas dynamics question you can usually ignore body forces such as gravity at chemical engineering scales.

If this is a liquids questions then a body force such as gravity may well come into play.

Remember in chemical engineering other body forces are often also in play.
 

FAQ: Momentum balance derivation in equations

What is momentum balance derivation in equations?

Momentum balance derivation in equations is a mathematical process used in physics and engineering to analyze the forces acting on a system and determine the resulting motion. It involves applying Newton's second law of motion, which states that the net force acting on an object is equal to its mass multiplied by its acceleration.

What is the purpose of momentum balance derivation in equations?

The purpose of momentum balance derivation in equations is to understand and predict the motion of a system based on the forces acting on it. This is important in many fields, such as fluid dynamics, aerodynamics, and structural mechanics, as it allows us to design and analyze systems and structures for various applications.

What are the key equations used in momentum balance derivation?

The key equations used in momentum balance derivation are Newton's second law of motion, the conservation of momentum, and the equations for calculating different types of forces, such as gravitational, frictional, and drag forces. These equations are used to set up and solve the equations of motion for a system.

What are some common assumptions made in momentum balance derivation?

Some common assumptions made in momentum balance derivation include the neglect of air resistance, assuming a constant mass or density, and assuming a rigid body. These assumptions are often made to simplify the equations and make them more manageable, but they may not accurately represent the real-world system.

How is momentum balance derivation applied in practical situations?

In practical situations, momentum balance derivation is used to design and analyze various systems and structures, such as aircraft, ships, and bridges. It is also used in fluid dynamics to study the flow of fluids in pipes, channels, and around objects. In addition, momentum balance derivation is used in sports, such as in the analysis of the motion of a golf ball or a tennis racket.

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