Question

Streamline flow is more likely for liquids with

• A. high density and high viscosity
• B. low density and low viscosity
• C. high density and low viscosity
• D. low density and high viscosity

Answer 1

The correct option is D low density and high viscosity

We know that, if Reynolds number
$N<2000\to$ flow is streamline
$N>3000\to$ flow is turbulent
and Reynolds number
$N=\frac{\rho vD}{\eta }$ where $\rho$ is density, $v$ is velocity, $D$ is diameter of tube and $\eta$ is co-efficient of viscosity of fluid.
$\Rightarrow N\propto \rho \&N\propto \frac{1}{\eta }$
For streamline flow, to have low value of Reynolds number, density of fluid should be low and viscosity should be high.