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

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SUMMARY

The discussion centers on the fluid flow and momentum equations, specifically the correct formulation of forces acting on a fluid. The equations presented include F1x and F3x, which relate to pressure and area, and their respective contributions to the resultant forces Rx and Ry. A critical point raised is the improper addition of area to pressure due to differing units, emphasizing the need for clarity in labeling forces and resultants in diagrams. The user also references external resources to support their understanding of forces in pipe bends.

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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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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.
 

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