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The hydrodynamic entrance length for laminar flow in a tube is linearly proportional to Reynolds number, Re, while turbulent flow is approximately independent of Re.

a. True
b. False

User Witson
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1 Answer

2 votes

Answer:

B. False

Step-by-step explanation:

In laminar flow, the Reynolds number (RE) is less than 2100 while in turbulent flow, it is greater than 4000.

Now,the entrance lengths for both laminar and turbulent flow is usually dependent on Reynolds number.

Thus is because the hydrodynamic entrance length for laminar flow is given by the formula;

Le = 0.05 DRe

Where;

Le is hydrodynamic entrance length

D is diameter of tube

Re is Reynolds number

Meanwhile, for turbulent flow, entrance length is given by;

Le = 1.359D(Re)^(1/4)

In both cases, we can see that the hydrodynamic entry length is directly proportional to the Reynolds number and not independent. Thus, we can say that the statement in the question is false.

User Andre Paap
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