Question

Water flows in a tube that has a diameter of D= 0.1 m. Determine the Reynolds number if the average velocity is 10 diameters per second. (b) Repeat the calculations if the tube is a nanoscale tube with a dimeter of D= 100 nm

Answer 1

Answer:

a) 89300

b) $8.93*10^-^8$

Explanation:

To find the Reynolds number, we use the formula:

Re = VD / v

Therefore, For part (a)

we are given:

D= 0.1

V= 10 * 0.1(m/s) = 1m/s

$v= 1.12*10^-^6 m^2/s$

Substituting the figures in the formula, we have:

$R_e = [(1m/s) (0.1m)] / 1.12*10^-^6 m^2/s$

Re = 89,300

For part (b)

We are given:

$D= 100nm * (1/10^9) = 10^-^7$;

$V = 10 * (10^-^7m/s) = 10^-^6$;

$v = 1.12*10^-^6 m^2/s$

Therefore,

$R_e = [(10^-^6) (10^-^7)] / 1.12*10^-^6$;

$R_e = 8.93*10^-^8$