Hele Shaw's Experiment Essay

1. Introduction

In this experiment, the Hele Shaw apparatus was used to determine the potential flow of different shapes. These shapes included an aerofoil, a circle, a triangle, a water droplet and a rectangle placed in both a horizontal and vertical position. The potential flow of a source, sink and a doublet were also examined.

1.1 Aim

Demonstrating the use of the Hele Shaw apparatus was the main objective of this experiment and it was used to demonstrate the various potential flow fields of the different obstacles.

2. Literature review

A Hele Shaw apparatus is used to visualize the potential flow of a two dimensional shape. The apparatus produces a steady and laminar flow of streamlines. The apparatus consists of a channel which

The streamlines then deflect and flow around the source. The velocity of the fluid at the stagnation point is zero while the velocity of the fluid around the source is greater than the velocity of the fluid before the source. Figure 4: Effect of a source on the streamlines [2]
Figure 5 theoretically shows what the velocity potential of a source should look like.

Figure 5: Flow around a half body [3]

A doublet, which is a combination of both a source and a sink, is shown in figure 6. One can see that the potential flow of a doublet is the same as if a source and a sink were superimposed.

Figure 6: Potential flow of a doublet [2]

In figure 7, one can see what a tear drop looks like when it is subjected to a uniform flow in theory. The fluid flows around the stationary shape where it then starts to separate from the body. This separation then causes a wake behind the tear drop. Figure 7: A tear drop in a uniform flow [3]
The potential flow for a vertical rectangle can be seen in figure 8 below. The flow of the streamlines that collide with the center of the rectangle does not flow past the rectangle. This causes a stagnation point and allows the streamline around it to flow along the rectangle and over the top and bottom of the