Fluid Mechanics - Practice Test

[#556] In case of turbulent flow of a Newtonion fluid in a straight pipe, the maximum velocity is equal to (where, V avg = average fluid velocity)

(A) V avg

(B) 1.2 V avg

(C) 1.5 V avg

(D) 1.8 V avg

Correct Answer

(B) 1.2 V avg

[#557] For Laminar flow through a packed bed, the pressure drop is proportional to (V s is the superficial liquid velocity and D p is the particle diameter)

(A) $$frac{{{{ ext{V}}_{ ext{s}}}}}{{{{ ext{D}}_{ ext{p}}}^2}}$$

(B) $$frac{{{{ ext{V}}_{ ext{s}}}^2}}{{{{ ext{D}}_{ ext{p}}}^2}}$$

(C) $$frac{{{{ ext{V}}_{ ext{s}}}^2}}{{{{ ext{D}}_{ ext{p}}}^3}}$$

(D) $$frac{{{{ ext{V}}_{ ext{s}}}}}{{{{ ext{D}}_{ ext{p}}}^3}}$$

Correct Answer

(A) $$frac{{{{ ext{V}}_{ ext{s}}}}}{{{{ ext{D}}_{ ext{p}}}^2}}$$

Explanation

Solution: For laminar flow in a packed bed (imagine a pipe filled with small balls), the pressure drop (how much the pressure decreases as the fluid flows) depends on how fast the fluid is moving and the size of the balls. Ergun Equation describes this relationship. For laminar flow, a simplified version of the Ergun equation is used. This simplified version shows that the pressure drop is directly proportional to the superficial velocity (Vs) and inversely proportional to the square of the particle diameter (Dp). Superficial velocity (Vs) means the velocity of the fluid if the bed were empty. Particle diameter (Dp) is the size of the balls in the packed bed. Therefore, if the superficial velocity increases, the pressure drop increases. If the particle diameter increases, the pressure drop decreases (because bigger particles offer less resistance to flow). Looking at the options, only option A shows this direct proportionality to Vs and inverse proportionality to the square of Dp (Dp 2 ). Option A: Vs/Dp 2 correctly represents this relationship for laminar flow in a packed bed.

[#558] The equation given below is called the __________ . $${{ ext{f}}^{ - 0.5}} = 4.07,{log _{ ext{e}}}{left( {{{ ext{N}}_{{ ext{Re}}}}sqrt { ext{f}} }
ight)^{ - 0.6}}$$

(A) Colebrook formula

(B) Von-Karman equation

(C) Fanning equation

(D) None of these

Correct Answer

(B) Von-Karman equation

[#559] The fluid velocity varies as the square root of the cylindrical pipe diameter in case of steady state laminar flow at constant pressure drop fo __________ fluid.

(A) Dilatant

(B) Pseudo-plastic

(C) Bingham plastic

(D) Newtonion

Correct Answer

(A) Dilatant

[#560] Permanent loss in a venturimeter is about __________ percent of the pressure drop in theupstream cone.

(A) 1

(B) 10

(C) 40

(D) 70

Correct Answer

(B) 10

Fluid Mechanics - Study Mode

[#556] In case of turbulent flow of a Newtonion fluid in a straight pipe, the maximum velocity is equal to (where, V avg = average fluid velocity)

Correct Answer

[#557] For Laminar flow through a packed bed, the pressure drop is proportional to (V s is the superficial liquid velocity and D p is the particle diameter)

Correct Answer

Explanation

[#558] The equation given below is called the __________ . $${{ ext{f}}^{ - 0.5}} = 4.07,{log _{ ext{e}}}{left( {{{ ext{N}}_{{ ext{Re}}}}sqrt { ext{f}} } ight)^{ - 0.6}}$$

Correct Answer

[#559] The fluid velocity varies as the square root of the cylindrical pipe diameter in case of steady state laminar flow at constant pressure drop fo __________ fluid.

Correct Answer

[#560] Permanent loss in a venturimeter is about __________ percent of the pressure drop in theupstream cone.

Correct Answer

[#558] The equation given below is called the __________ . $${{ ext{f}}^{ - 0.5}} = 4.07,{log _{ ext{e}}}{left( {{{ ext{N}}_{{ ext{Re}}}}sqrt { ext{f}} }
ight)^{ - 0.6}}$$