Fluid flow and momentum equation. Do I have the right equation?

In summary, the conversation discusses the equations for calculating the resultant forces in a pipe bend, taking into account pressure, area, density, and flow rate. The equations involve adding pressure and area in some cases, but this is incorrect due to unit differences. The diagram should be labeled to distinguish between F (force) and R (resultant force). The information is based on the concept of forces in pipe bends, as explained in the provided link.
  • #1
defdek
12
0
http://img89.imageshack.us/img89/3914/unled23g.png F1x+F3x = density x Q(Vx2 – Vx1)
F1x = -Rx
F3x= (pressure 1 x area 1) + (Pressure 2 x area 2) (Cos B)
F1y+F3y = density x Q(Vy2 – Vy1)
F1y = -Ry
F3y = (Pressure 2 + Area 2)(Cos B)
So is it:
Rx= (pressure 1 x area 1) + (Pressure 2 x area 2) (Cos B) - density x Q(Vx2 – Vx1)
Ry = (Pressure 2 + Area 2)(Cos B) - PQ(Vy2 – Vy1)
 
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  • #2
For starters, I see that in two cases you are adding area to pressure. This cannot be done because units are different. You should label your diagram as to what is F and what is R.
 
  • #3
Last edited:

1. What is the equation for fluid flow and momentum?

The equation for fluid flow and momentum is known as the Navier-Stokes equation, which describes the motion of a fluid in terms of its velocity, pressure, density, and viscosity.

2. How is the Navier-Stokes equation derived?

The Navier-Stokes equation is derived from the fundamental laws of physics, including Newton's second law of motion, the continuity equation, and the conservation of momentum equation.

3. Can the Navier-Stokes equation be used for all types of fluids?

The Navier-Stokes equation is a general equation that can be used to describe the motion of both Newtonian and non-Newtonian fluids. However, it may need to be modified for specific types of fluids, such as highly viscous or compressible fluids.

4. What are some applications of the Navier-Stokes equation?

The Navier-Stokes equation is used in a wide range of applications, including aerodynamics, hydrodynamics, weather prediction, and fluid dynamics in engineering and industrial processes.

5. How accurate is the Navier-Stokes equation?

The Navier-Stokes equation is highly accurate in predicting fluid flow and momentum under certain conditions. However, it may not always provide an exact solution due to simplifications and assumptions made during its derivation. In some cases, additional equations or numerical methods may be needed for more precise results.

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