# What Is the Difference between Source Flow and Sink Flow?

### What is source flow?

Source flow is defined as the two-dimensional flow coming from a point called source and moving out radially on a plane in a uniform rate. Fig.a represents a source flow. Here point O is the source. From source, fluid is flowing radially in all direction of plane. The strength of the source, q is defined as the volume flow rate per unit depth of fluid. The unit of source strength is m^{2}/s.

### Relationship between radial velocity and strength of source

Let q= strength of sourcer = radius from the source O

u

_{r}= radial velocity of fluid at radius r

The equation of radial velocity ur at radius r is given by

u

_{r}= q/2πr

Above equation shows that the radial velocity of fluid varying inversely as radius increases. For a high value of r, ie at large distance, the radial velocity will be equal to zero.

### What is sink flow?

Sink flow is literally opposite to the source flow. In sink flow, fluid moves radially inward (or absorbs fluid) towards a point known as sink, and fluid disappear at sink at a constant rate. Fig.b shows a sink flow, the point O is known as sink. The equation of radial velocity in sink flow is similar but with a sign change to q.The equation of radial velocity u

_{r}at radius r is given by

u

_{r}= -q/2πr

👉 In source flow and sink flow, there is no tangential velocity.

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