Engineering Hydrodynamic force on hinged flap gate

AI Thread Summary
The discussion focuses on calculating the hydrodynamic forces on a hinged flap gate using the conservation of momentum. The user seeks an equation applicable for all angles, addressing both static and dynamic scenarios. There is uncertainty about the definitions of forces F1 and F_hydro, as well as the appropriate coordinate system for analysis. The conversation emphasizes the importance of clarity in problem-solving to avoid confusion in the analysis. The user also questions whether the analysis should consider water flow or only the moment of gate opening.
Kapper
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Homework Statement
I am trying to find an expression for the hydrodynamic torque the water is exerting on a hinged flap gate. the gate is partially submerged and water can flow around the gate in all directions. I Am not sure how to set up this equation
Relevant Equations
Conservation of momentum, Hydrostatic pressure
I have attempted to use the law of conservation of momentum.

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The Areas are the lengths marked with the red striped line times the length into the paper, and the Forces F1 and F_hydro are the hydrostatic pressure and hydrodynamic forces respectively (acting on the plate) (The x y components is relative to the coordinate frame given in drawing).

I want to have an equation that works for all angles, which includes both static and dynamic situations.
I can't get this to make sense I think I should use angular momentum instead of linear But I have no idea how to derive that.
 
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What is F1, or FHydro?
And what coordinate system orientation are you using?

That is the first step in solving thee problems so that others are not guessing on the analysis.

Other than that, are you being asked to solve the force with water flow, or just at the instance when the gate will open?
 
Sorry I've made an update
 
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