Total force on surface of a plate?

AI Thread Summary
To find the total force on the surface of a plate, the shear stress at each point must be calculated using the equation T = μ * u'(y), where μ is the viscosity and u'(y) is the velocity gradient. Since the velocity distribution varies along the plate, the shear stress will differ at each point, leading to a total force calculated as the sum of μ * u'(y=0) * A across the plate's surface. The integral for the total force is set from 0 to L, incorporating the width and differential length (dl). If the flow affects both sides of the plate, the total force is simply double this integral. Understanding these principles is crucial for accurately determining the forces acting on the plate.
eterna
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Homework Statement


http://scienceofdoom.files.wordpress.com/2010/12/convection-basics-1b.png

How do I find the total force on that surface of the plate?

Homework Equations



T = μ * u'(y)

where T is the shear stress, μ is a scalar constant - the viscosity and u'(y) is the velocity gradient in the perpendicular direction

Force = T * A

The Attempt at a Solution


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Does every point along the plate have a different u(y) distribution so that the shear stress at the surface, μ * u'(y=0) , is different for all of these points?
And so the total force is the sum of μ * u'(y=0) * A for all of those points?
 
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Yes.

Chet
 
So is the correct integral

from 0 to L(length of the plate) : μ u'(0) width dl ?And so for the total force( top + bottom of plate), is it just two times that?
 
Yes, if the flow is on both sides of the plate.

Chet
 
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