Volume flow rate is used in physics to describe the flow of fluids (of particular volume). It provides the flow rate in terms of the body’s physical dimensions. It does not directly depend on the mass that travels through the given space. In most cases, the volume flow rate only applies to gases and liquids. It doesn’t count for solids, even if some solid moves at a considerable steady rate.
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What is Volume Flow Rate?
Volume flow rate is the fluid’s volume which flows per unit time. It is generally denoted by the symbol ”Q” (occasionally ”V”). It is much different from the concept of “mass flow rate”. It does not consider mass as an influencing factor. In most scenarios, consideration of fluid flow rate typically points to volume flow rate. The SI unit of volume flow rate is cubic metres per second.
This flow rate is controlled by the limit.
This is the flow of volume of the given fluid “V” passing via a surface per unit time “t”. As this is only the volume’s time derivative, it is under the category of a scalar quantity. Therefore, the volume flow rate is undoubtedly a scalar quantity. The variation in volume is the quantity that flows after passing the boundary for a particular time duration, not plainly the initial quantity of volume at the border minus the final amount at the borderline since the variation in volume moving through the area would be zero in the case of steady flow.
As volume flow rate calculates the amount of volume that flows into an area per time, the equation for this flow rate will behave like the ratio of volume to time. It is worth noting that there is another useful way of denoting the volume flow rate like this. The rate will be higher when the involved cross-section of the pipe becomes narrower. It implies that the fluids accelerate when they pass through a narrow section of the pipe and considerably decelerate when they pass through a wider cross-section of the pipe.
Volume Flow Rate Equation
The volume flow rate equation is,
There is another way to describe and represent volume flow rate. The volume of a section of the fluid inside a pipe can be represented as V=Ad. Here ‘A’ is the area of the cross-section and ‘d’ is the width of the fluid portion. Substitute this formula into the conventional volume flow rate equation.
The fraction d/t is merely the length of the fluid volume divided by the time period of fluid flow through its length (speed of the fluid). Thus, d/t can be replaced by ‘v’ in the earlier equation. This results in the below equation,
The video explains the mechanical properties of fluids
Liquid Incompressibility
From the available practical evidence, it is known that most liquids are almost incompressible. This implies that a litre of honey can be stored in a differently shaped one-litre container. But it is very difficult to compress the entire litre of honey into a half litre container no matter how much force is applied. This is valid in almost all cases, as any quantity of liquid passing through a tube could adjust to the available shape, but it should maintain the default volume. This is valid even if the tube varies in diameter. A liquid (volume ‘V’) maintains the same volume even if it enters a narrower cross-section of the pipe.
Mass Flow Rate
In some scenarios, it is required to find the amount of mass that flows through the system. This aspect is crucial in engineering and applied physics, where it is essential to know how much weight a pipe or reservoir can efficiently and safely hold. Mass flow rate is the mass of a material which flows per unit of time. Its SI unit is kilogram per second. Depending on the situation, the mass flow rate is also termed
as mass current or mass flux.
Mass flow rate is given by the limit:
It is the flow of mass ‘m’ through the given surface per unit time.
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Frequently Asked Questions
What is meant by the flow?
Flow is usually defined as the rate of change of volume or mass.
What is meant by the volume flow rate?
Volume flow rate is the fluid’s volume which flows per unit time. It is generally denoted by the symbol ”Q” (occasionally ”V”). It is much different from the concept of “mass flow rate”. It does not consider mass as an influencing factor.
What is the SI unit of the volume flow rate?
The SI unit of volume flow rate is cubic metres per second.
Explain the compressibility of liquids.
From the available practical evidence, it is known that most liquids are almost incompressible. This implies that a litre of honey can be stored in a differently shaped one-litre container. But it is very difficult to compress the entire litre of honey into a half litre container no matter how much force is applied.
Does the mass of a fluid directly influence the volume flow rate?
No, mass doesn’t directly influence the volume flow rate.
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