Dimensional Analysis homogeneous

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SUMMARY

The discussion focuses on determining the dimensional homogeneity of the equation ΔP/Q = 17L(μ)/(w^4), where ΔP represents pressure drop, Q is volumetric flow rate, L is channel length, μ is fluid viscosity, and w is the side length of a triangular channel. Participants analyze the dimensions of ΔP and Q, concluding that ΔP has dimensions of ML(T^-2) and Q has dimensions of L^3/T. The correct dimensional analysis leads to ΔP/Q having dimensions of M(T^-1)(L^-4), while fluid viscosity μ is clarified to have units of kg/(m⋅s), and the unitless constant 17 is deemed ignorable.

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Larrytsai
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Determine which of the following equations are dimensionally homogeneous. Show
your work
ΔP/Q = 17L(μ)/(w^4)


where ΔP is the pressure drop in a channel of triangular cross-section, Q is the
volumetric flowrate, L is the channel length, μ is the fluid viscosity, and 2w is the
length of one side of the trianglei have

ΔP = F/A = ML(T^-2)
Q = volume/seconds = (L^3)/T

so...

ΔP/Q = M(T^-1)(L^-4)

For the other side of the equation I do not know how to deal with fluid viscosity and do I ignore the 17?
 
Last edited:
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The viscosity, μ, has units of Pa⋅s, or (N⋅s)/m2, or kg/(m⋅s). Yes, ignore the unitless constant 17.

ΔP = F/A = ML(T^-2)

does not look right.
 
Thank you so much I have spotted the problem
 

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