flows what we had seen earlier is the fluid, ideal and real fluid. Now, flows are given
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here 8 forms, but there are some combinations that are also possible.
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So we will just examine one by one, the types of flow, the steady and unsteady flow. Fluid
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characteristics such as velocity, pressure, density, temperature etcetera, at any point
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do not change in time. For example, water moving with a constant distance discharge
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rate so, at any point when you consider the flow of water with constant discharge rate
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or in general that is only an example, in general first, this kind of a flow at any
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point x y z the rate of change with respect to time, the rate of change of the property
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which we are discussing theta u p or dou rho with respect to time is zero that is do not
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change with time. If, it is a changing with time if, it changes
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with time what is it? Unsteady flow. So, for example, if it changes with time then for
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example, here I have taken the behavior of ocean waves. What do you mean by behavior?
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Why ocean waves are unsteady? You will see that later how a wave varies, In the case
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of a regular wave, if you measure the waves in the deep ocean so, this is the surface
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elevation and you see that the surface elevation is going to vary with respect to time. When
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you measure the open ocean or if you later you will also see that the waves are can be
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this kind of a wave can approximately said to be represented can be represented as a
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sinusoidal wave.
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So, these waves you see that when they are moving on the surface it will have its particle
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velocities and other characteristics that will be changing within the fluid medium.
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So, all those changes like the change with the pressure etcetera or velocities will all
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be changing with respect to time. So, that is why we say that it is an unsteady flow.
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Now, Uniform Flow: At any given instant of time, when the fluid particles as stated earlier
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u, pressure, density etcetera does not change in both magnitude and direction from point
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to point not from time to time from point to point within the fluid, the flow is said
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to be that is why we are showing it as dou u by dou s. S is with respect to space. So,
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the variation of velocity with respect to space at any given of point of time is going
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to be equal to 0.
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So, Non-Uniform Flow: If the velocity changes, if the velocity of fluid, when I say velocity
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it also includes the other properties of the fluid. If the velocity of fluid changes from
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point to point at any given time instant, then it is called as non-uniform flow the
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ones which are having the red color font that shows only the examples for the different
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kind of flows. Here in the case of non-uniform flow, flow of liquid under pressure through
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long pipe lines of varying diameter. Suppose, if the diameter is constant, if this diameter
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is constant, the same flow of fluid under pressure will be uniform flow.
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So, now this is constant dia and now, we have varying dia. That is going to take care of
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whether the flow is going to be non-uniform or uniform. Now, under steady or unsteady
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and uniform or non-uniform, flow can exist independently of each other that is you can
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hither steady or unsteady, uniform or non-uniform, but they can also have combinations combinational
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are also possible. So, for example, if you have a flow of liquid
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under a constant rate and it is in a long pipe line constant diameter. So, you see that