Chemical Engineering - Fluid Mechanics - Discussion

Discussion Forum : Fluid Mechanics - Section 1 (Q.No. 2)
Laminar flow of a Newtonion fluid ceases to exist, when the Reynolds number exceeds
Answer: Option
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14 comments Page 1 of 2.

JayaMsuba said:   9 years ago
For open channel flow,

If Re <500 or 600. laminar
> 2000 or 2100. turbulent.
Here, Re=rho*v*R/mu...R=hydraulic gradient.

For circular pipe flow,

If Re <2000. laminar.
> 4000. turbulent.
Here, Re=rho*v*d/mu...d=dia of pipe.

Here both formulae are important to keep in mind. because sometime this may confuse you.

Surya Teja said:   7 years ago
Let is assume the question is for circular pipe based on options given. But, the question is when will the Laminar flow cease? I think, once the fully turbulent flow is achieved, which is after crossing Re 4000. Then only we can say there is no laminar flow.

B.Nath said:   1 decade ago
For flow in a conduit:
Re<2100 Laminar Flow, Sheer Stress depends on viscosity but not on density.
2100<Re<4000 : Transient Flow
Re>4000 Turbulent flow depends on density.

Chitta said:   1 decade ago
The above question doesn't mention about the system.
we have two type of value for laminar.

1. for circular pipe----- Re<= 2100
2. for flat plate ------- Re<= 5*10^5

Mahone said:   6 years ago
For circular pipes, the Reynolds number is used to classify flows as follows.

<2000 laminar flow.
2000-4000. Transitional flow.
>4000 turbulent flow.

Khawal said:   9 years ago
Laminar flow is in linear motion and having re less than 2100, after increase the re the turbulence is so that velocity increase.

Jyoti said:   1 decade ago
This is true only in case of flow through pipes. we cannot generalize this for every case. Re num is different for every case.

Kalaivani said:   10 years ago
For Laminar flow, Reynold's number is less than or equal to 1(Re <= 1).

Dhruvin virani said:   10 years ago
Laminar flow is less than or equal to 2100. And Re>4000 Turbulent flow.

Mishree lal said:   3 years ago
For laminor flow Reynolds number is equal or less than 2100.

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