Water is flowing placidly in a canal at a depth of 2 cm and a width of 2 m with a velocity of
4 m/s. It's a nice sunny day in Arizona near Phoenix in the summertime. Is the flow laminar or turbulent?
A) Laminar
B) Turbulent
C) It can alternate between being laminar and turbulent
D) Insufficient information to decide

Question

Quizplus · Accepted Answer

$\text {Turbulent}$
$\text {In the summer near Phoenix, the temperature is between $40 ^ { \circ } \mathrm { C }$ and $50 ^ { \circ } \mathrm { C }$. Table B.1 }$$\text {gives the kinematic viscosity about $0.6 \times 10 ^ { - 6 } \mathrm {~m} ^ { 2 } / \mathrm { s }$. The Reynolds number is}$
$$\operatorname { Re } = \frac { V h } { v } = \frac { 0.4 \mathrm {~m} / \mathrm { s } \times 0.02 \mathrm {~m} } { 0.6 \times 10 ^ { - 6 } \mathrm {~m} ^ { 2 } / \mathrm { s } } = 13300$$
$\text {which represents turbulent flow. The width of the channel is unimportant. Even if}$ $\text {the flow were in Michigan where the temperature could be as low as $10 ^ { \circ } \mathrm { C }$, the flow }$$\text {would be turbulent.}$

Water Is Flowing Placidly in a Canal at a Depth