Problem 41 - Master Resource Book in JEE Main Physics

Question

Streamline flow is more likely for liquids with |NCERT Exemplar ] (a) high density (b) high viscosity (c) low density (d) low viscosity

Step-by-Step Solution

Answer

Streamline flow is more likely for liquids with high viscosity.

Step 1: Understand the Concepts

Streamline flow, also known as laminar flow, occurs when a fluid flows in parallel layers without disruption between the layers. It is characterized by the fluid particles moving in an orderly path or streamline. In contrast, turbulent flow is chaotic and occurs when the flow velocity increases past a certain point or with fluids of low viscosity.

Step 2: Analyze the Effect of Density

Density is the mass per unit volume of a fluid. It affects the fluid flow; however, its primary influence is on the gravitational force acting on the fluid. High density does not directly ensure streamline flow since streamline flow is more sensitive to viscosity.

Step 3: Analyze the Effect of Viscosity

Viscosity is a measure of a fluid's resistance to deformation. High viscosity implies a greater resistance to flow, enhancing the likelihood of orderly, laminar flow because it dampens velocity fluctuations. Therefore, streamline flow is more likely with high viscosity fluids.

Step 4: Review the Options

Given (a) high density, (b) high viscosity, (c) low density, and (d) low viscosity, the presence of high viscosity tends to promote laminar flow by reducing the chances of turbulence.

Step 5: Select the Best Choice

Considering the factors influencing streamline flow, the best choice is (b) high viscosity, as it promotes a more orderly and stable flow.

Key Concepts

Streamline Flow

Imagine water flowing through a narrow pipe, moving along smooth paths without any random swirls or eddies. This is what we call streamline flow, or laminar flow, where the fluid travels in parallel layers without mixing. Each particle of the fluid follows a path known as a streamline.
In streamline flow, every layer of fluid moves smoothly past adjacent layers. The paths do not converge or separate, which means there's little to no disruption between the layers. This orderly movement of particles is contrasted by turbulent flow, where chaotic changes in pressure and flow velocity occur.
Streamline flow is incredibly important in many engineering applications, such as the design of pipelines and aircraft wings, where smooth and efficient movement of fluid is essential. It's characterized by lower flow rates and a higher chance of occurring when certain conditions, like high viscosity, are met. Understanding streamline flow helps engineers reduce energy loss and improve overall system performance.

Viscosity

Viscosity is like a fluid's "thickness" or resistance to flow. Imagine trying to pour honey out of a jar; it flows slowly and resists movement due to its high viscosity. Now, think about water, which pours easily, showing low viscosity.
Viscosity determines how easily layers of fluid slide past one another. A high viscosity means the fluid layers face great resistance, which in turn reduces velocity irregularities and prevents chaotic flow, fostering streamline or laminar movement.
This property is crucial in determining how fluids behave under different conditions. For example:

• High viscosity fluids, like oils, often flow in a streamlined manner due to their resistance to changes in speed and direction.
• Low viscosity fluids, like gases, are more prone to turbulent flow, especially at higher velocities.

Control over viscosity is vital in industries such as lubrication and food processing, where the nature of flow can significantly affect quality and efficiency.

Laminar Flow

Laminar flow is all about consistency and order in the movement of fluid particles. In this type of flow, particles move in perfectly straight paths or layers without mixing. The entire flow is smooth, orderly, and predictable, resembling the imaginary lanes of a well-organized highway.
Laminar flow typically occurs under conditions where fluid velocities are low, or the fluid is highly viscous. This state is desirable in many situations because it minimizes friction and energy loss, which can increase system efficiency.
Some environments where you might find laminar flow include:

• In narrow pipes where fluids like oil move at a steady pace.
• In blood vessels, where blood must flow smoothly and efficiently.

Achieving laminar flow is beneficial because it helps prevent wear and tear in mechanical systems and aids in delivering precise fluid measurements.