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Chemical Engineering - Heat Transfer - Discussion

Discussion Forum : Heat Transfer - Section 2 (Q.No. 26)
Heat Transfer
26.
For flow over a flat plate, the ratio of thermal boundary layer thickness, 'xt' and hydrodynamic boundary layer thickness 'x' is equal to (where, NPr = Prandtl number)
NPr
NPr1/3
NPr-1
NPr-1/3
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
13 comments Page 1 of 2.
Miswahul haq said:   11 months ago
By comparing the equations for the thermal and hydrodynamic boundary layers, it can be shown that the ratio of 'xt' to 'x' is equal to the inverse of the Prandtl number raised to the power of one-third: xt/x = NPr^ (-1/3).

Therefore, the correct answer is option 'B', NPr^ (1/3).
(1)
Anuj said:   1 year ago
The Correct answer is Npr^-1/2.
Vishwaraj said:   6 years ago
The correct answer is D. I too agree.
Sai prasad said:   7 years ago
The ratio of Prandtl number says that it is the ratio of the hydrodynamic boundary layer or momentum diffusivity to the thermal boundary layer or thermal diffusivity.

So, therefore pr=momentum diffusivity/thermal diffusivity
And when the pr number is reciprocal ie is hydrodynamic boundary layer/thermal boundary layer.
And pr no=1 means x=xt.
So, x/xt=pr*1.
X=xt*pr.
Therefore clearly it is when pr^-1 it is xt/x.
Utkarsh said:   7 years ago
Yes, the correct answer would be D.
Heera singh said:   7 years ago
The answer is D.
Yadav said:   7 years ago
I think [D] is the correct option.
Ashish said:   7 years ago
I am totally agree @Dipankar.
(1)
Dipankar Kakati said:   7 years ago
(Hydrodynamic Boundary Thickness)/(Thermal Boundary Thickness) = Pr^(1/3).
So, Answer is D.
Turbulence said:   8 years ago
According to me, the answer is D.
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