Chemical Engineering - Heat Transfer - Discussion
Discussion Forum : Heat Transfer - Section 2 (Q.No. 26)
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)
Discussion:
13 comments Page 1 of 2.
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.
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.
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).
Therefore, the correct answer is option 'B', NPr^ (1/3).
(1)
KOSISOCHUKWU said:
9 years ago
The answer is C.
The Prandtl number is defined as the ratio of hydrodynamic boundary layer thickness to thermal boundary layer thickness. It is therefore clearly seen that this is the inverse of the problem statement.
The Prandtl number is defined as the ratio of hydrodynamic boundary layer thickness to thermal boundary layer thickness. It is therefore clearly seen that this is the inverse of the problem statement.
(1)
Dipankar Kakati said:
7 years ago
(Hydrodynamic Boundary Thickness)/(Thermal Boundary Thickness) = Pr^(1/3).
So, Answer is D.
So, Answer is D.
Vishwaraj said:
6 years ago
The correct answer is D. I too agree.
Utkarsh said:
7 years ago
Yes, the correct answer would be D.
Yadav said:
7 years ago
I think [D] is the correct option.
Turbulence said:
8 years ago
According to me, the answer is D.
Ash said:
1 decade ago
Answer is D.
xt/x = 1/Npr^1/3.
xt/x = 1/Npr^1/3.
Anuj said:
1 year ago
The Correct answer is Npr^-1/2.
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