Chemical Engineering - Fluid Mechanics - Discussion
Discussion Forum : Fluid Mechanics - Section 1 (Q.No. 26)
26.
A particle A of diameter 10 microns settles in an oil of specific gravity 0.9 and viscosity 10 poise under Stoke's law. A particle B with diameter 20 microns settling in the same oil will have a settling velocity
Discussion:
22 comments Page 1 of 3.
TANMAY SHAH said:
2 years ago
The settling velocity, and, as a result, settling time, are proportional to the diameter of the spherical particle squared.
The larger the sphere diameter, the faster the particle will settle.
The smaller the particle diameter, the longer it will stay suspended in the fluid.
So, V2/V1 = (D2)^2/(D1)^2.
V2/V1 = 20^2/10^2,
V2 = 4 V1.
So, option-D is the right answer.
The larger the sphere diameter, the faster the particle will settle.
The smaller the particle diameter, the longer it will stay suspended in the fluid.
So, V2/V1 = (D2)^2/(D1)^2.
V2/V1 = 20^2/10^2,
V2 = 4 V1.
So, option-D is the right answer.
(13)
Sandy said:
9 years ago
Am afraid am wrong settling velocity is nothing but terminal velocity, therefore, terminal velocity is directly proportional to diameter square answer should be D if they ask about the only velocity without mentioning terminal velocity then the answer would be B that is Velocity is inversely proportional to diameter square.
Zeeshanulhaq said:
6 years ago
At low Reynolds number settling velocity is proportional to square of dp, then d is answer. While for very low or very high Reynolds velocity is proportional to underroot dp.
Daniel said:
1 decade ago
This is wrong answer.
Vt is proportional to square of dia.
So if dia is doubled, Vt should be four times not one - fourth of original.
Vt is proportional to square of dia.
So if dia is doubled, Vt should be four times not one - fourth of original.
Lucy said:
1 decade ago
Vt = (g*dp^2*(raup - rauf))/(18*(viscocity)).
Where dp = diameter of particle.
raup = density of particle.
rauf = density of fluid.
Where dp = diameter of particle.
raup = density of particle.
rauf = density of fluid.
Abhay kumar Pandey said:
3 years ago
Settling velocity is directly proportional to the diameter of the particle (having an increasing trend).
Manoj said:
8 years ago
No the answer is (1/4) A.
v = R2
v = (2d)2
v = 4d2.
Now, v is doubled so,
2v = 8d2.
Hence v = (1/4) d2.
v = R2
v = (2d)2
v = 4d2.
Now, v is doubled so,
2v = 8d2.
Hence v = (1/4) d2.
Yash said:
3 years ago
Yes, D is correct, in the stokes region, settling velocity varies (D)^ (2).
Solving gives Vb= 4* Va.
Solving gives Vb= 4* Va.
May Saadoon said:
1 year ago
u(A)/u(B) = [dp(A)/dp(B)]^2.
u(A)/u(B) = [ 10 / 20 ] ^2.
u(A)/u(B) = 1/4,
u(A) = 1/4 u(B).
u(A)/u(B) = [ 10 / 20 ] ^2.
u(A)/u(B) = 1/4,
u(A) = 1/4 u(B).
(2)
Sandy said:
9 years ago
Velocity is inversely proportional to diameter.
Vb/Va= Da^2/Db^2
Vb/Va= 100/400
Vb= 1/4 Va
Vb/Va= Da^2/Db^2
Vb/Va= 100/400
Vb= 1/4 Va
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