Question

A doublet is the resulting flow pattern when a sink and a source of equal strength are brought together.
Which one of the following options correctly represents the nature of the product of the strength and the distance between them during approach?

• A. Remains always constant
• B. Continuously decreases
• C. Continuously increases
• D. First increases and then continuously decreases after reaching a maximum

Hint:

In a doublet, the product of the source and sink strength and the distance between them remains constant, regardless of how close they get to each other.

Answer 1

The Correct Option is A

A doublet is a flow pattern formed by placing a sink and a source of equal strength infinitesimally close together. The resulting flow has characteristics similar to a dipole, with the source and sink creating opposing effects in the flow. In fluid mechanics, a doublet is often used to model certain flow patterns around objects.
The product of the strength of the source and sink and the distance between them remains constant. This means that as the distance between the source and sink decreases, their combined strength also adjusts to maintain the same flow characteristics. The constant product ensures that the overall strength of the doublet is preserved, even though the source and sink are brought closer together.
Thus, the correct answer is (A) Remains always constant, because the total strength of the source-sink combination does not change as they approach each other.