Applying a pressure drop across a capillary results in a volumetric flow rate 'Q' under laminar flow conditions. The flow rate for the same pressure drop, in a capillary of the same length but half the radius is

A. $$\frac{{\text{Q}}}{2}$$

B. $$\frac{{\text{Q}}}{4}$$

C. $$\frac{{\text{Q}}}{8}$$

D. $$\frac{{\text{Q}}}{{16}}$$

Answer: Option D

This Question Belongs to Chemical Engineering >> Fluid Mechanics

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Comments ( 2 )

  1. Saurabh Motiwala
    Saurabh Motiwala :
    3 years ago

    According to Hagen Posuille equation for laminar flow
    ∆P=32 ulv/d^2. gc

    Then , v= ∆P. d^2. gc/32ul...............(1)
    We know that the volumetric flow rate given as Q= A.v..........(2)
    area for capillary can be given as π/4 d^2

    Put the value of v in eqn (2 )
    Q= ∆P . d^4.gc/32ul
    Q= (d/2)^4
    We know that half the radius then ,,,, Q= (r/2)^4
    Q= r^4/16

  2. Jolly Ghadage
    Jolly Ghadage :
    4 years ago


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