Chemical Engineering - Fluid Mechanics - Discussion
Discussion Forum : Fluid Mechanics - Section 4 (Q.No. 39)
39.
What is the shear rate at the pipe wall, in case of laminar flow of Newtonion fluids in a pipe of diameter 'D' & length 'L' incurring a pressure drop 'Δp' with average velocity 'Vavg'?
Discussion:
5 comments Page 1 of 1.
Suraj said:
4 years ago
No option C is correct.
Shear stress at wall = (ΔP/L)*(D/4)
ΔP/L= 32 *Vavg* viscosity/ D^2.
We get shear stress at wall = 8 * Vavg * viscosity/D.
Shear stress = viscosity * shear rate.
So the shear rate is 8 * Vavg/D.
Shear stress at wall = (ΔP/L)*(D/4)
ΔP/L= 32 *Vavg* viscosity/ D^2.
We get shear stress at wall = 8 * Vavg * viscosity/D.
Shear stress = viscosity * shear rate.
So the shear rate is 8 * Vavg/D.
(2)
Jayavel v said:
6 years ago
Option B is the correct answer, when we do momentum balance over fluid element we got ΔpD/4L.
Dhiraj jadhav said:
6 years ago
Option B is correct as (dp/dL+2T/rw) by momentum balance.
Dagger said:
9 years ago
As per my knowledge, option B is the right answer.
Atharv said:
4 years ago
Yes, absolutely correct @Suraj.
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