Question Video: Recognizing Steady Flow | Nagwa Question Video: Recognizing Steady Flow | Nagwa

# Question Video: Recognizing Steady Flow Physics • Second Year of Secondary School

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Is the fluid flow shown in the following figure turbulent in any part of the flow?

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### Video Transcript

Is the fluid flow shown in the following figure turbulent in any part of the flow?

In order to answer this question, we need to understand how this fluid’s flow can be modeled by these blue arrows and what is meant by turbulent flow.

Recall that we can model the overall motion of a fluid by representing the motion of different layers of the fluid using streamlines, which is what’s shown by the blue arrows here. Different fluid layers can flow at different speeds and in different directions.

Now, modeling a fluid quantitatively can be very complicated. But we are able to describe fluid flow qualitatively by observing its streamlines and characterizing the flow as steady or turbulent. These terms mean opposite things. Steady fluid flow is orderly and smooth. We can see this in a fluid whose layers generally move in the same direction and at the same speed as each other. When a fluid’s layers keep the same distance apart from one another, we can tell that there’s not a significant difference in speed between them. Conversely, turbulent fluid flow is especially chaotic. We see turbulence in a fluid whose layers change speed and direction rapidly, as shown by streamlines that are more curved or bunched together.

Now, this question is asking us whether the fluid shown in the figure is turbulent at any point in its flow. So let’s take a closer look at it. As a whole, we can see that the direction of the flow is changing because it’s moving around a bend. But this doesn’t necessarily mean that the flow is turbulent. Notice that each layer of the fluid changes its direction by the same amount. So the streamlines always stay the same distance apart.

Therefore, the layers of the fluid don’t have different directions relative to each other. This shows us that the fluid’s layers are moving together in a nice and orderly way. So the flow here is steady, not turbulent. So the answer to this question is no. The fluid flow shown in the figure is not turbulent in any part of the flow.

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