How to find the maximum flow velocity of turbulent flow and laminar flow?

Turbulence is fluid mechanics.

refers to a disordered state in which a fluid changes from one steady state to another. Specifically, it refers to the inertial force between the various particles when the fluid flows.

Dominated, the fluid flows irregularly at various particles.

Turbulent flow is generally relative to "laminar flow."

in other words. Reynolds numbers are generally used.

Decide. The small Reynolds number means that the viscous force between the particles is dominant when the fluid flows, and the fluid particles flow regularly parallel to the inner wall of the pipeline, showing a laminar flow state. The large Reynolds number means that the inertial force occupies the main position, and the fluid is in a turbulent flow state, and the general pipeline Reynolds number RE 2000 is the laminar flow state, RE 4000 is the turbulent flow state, and RE 2000 4000 is the transition state.

In different flow states, the movement law of the fluid and the distribution of the flow velocity are different, so the ratio of the average flow velocity to the maximum flow velocity of the fluid in the pipeline is also different. Therefore, the magnitude of the Reynolds number determines the flow characteristics of the viscous fluid.

When the fluid flows in the tube, its particles move in a smooth straight line in a direction parallel to the tube axis. This type of flow is called laminar flow or stagnant flow, and it is also called straight flow. The velocity of the fluid is greatest at the center of the tube and smallest near its walls.

The ratio of the average flow velocity to the maximum flow velocity of the fluid in the tube is equal to the flow state of the fluid in laminar flow when the Reynolds criterion is < 2100 according to the Reynolds test.

Laminar motion of viscous fluids. In this flow, there is no significant irregular pulsation in the trajectory of the fluid microclusters. There is only molecular thermal motion between adjacent fluid layers.

caused by the exchange of momentum. Common laminar flows include flow in capillary or porous media, flow in bearing lubrication film, flow in boundary layer around the surface of an object, etc. Laminar flow occurs only when the Reynolds number is small, i.e., the fluid density, the characteristic velocity u, and the characteristic length of the object l are all small, or the fluid viscosity is very large.

When the RE exceeds a certain critical Reynolds number RECR, the laminar flow begins to transition to irregular turbulence due to disturbance, and the movement resistance increases sharply. The critical Reynolds number depends mainly on the form of flow. For round pipes, RECR 2000, where the eigenvelocity is the average velocity on the cross-section of the round tube.

The characteristic length is the inner diameter of the round tube. Laminar flow is much simpler than turbulent flow, and most of its flow equations have exact, approximate and numerical solutions. Laminar flow is generally less frictional than turbulent flow, so in the design of aircraft or ships, the boundary layer flow should be kept laminar as much as possible.

That is to say, whether it is laminar or turbulent is not determined by velocity, but by the Reynolds number.

This needs to be evaluated by the Reynolds number (re), generally 2500 as the boundary, re>2500 turbulence.

There are two types of flow states of liquids, which are laminar flow and turbulent flow.

Laminar flow: It is the fluid flow that is layered, the cohesion plays a leading role, the liquid particle is constrained by the viscosity, and the energy loss is less and the flow is trapped.

Turbulent flow: It is the fluid flow that is mixed, the inertial force plays a leading role, the restraining effect of the cohesive force is weakened, and the energy loss is large during flow.

The flow state of the liquid is judged by the Reynolds coefficient, which is laminar when the Reynolds coefficient is rerec, and turbulent when the Reynolds coefficient is rerec.

When the fluid flows at low velocity in the tube, it appears as laminar flow, and its particles move in a smooth straight line along the direction parallel to the tube axis. The velocity of the fluid is greatest at the center of the tube and smallest near its walls. The ratio of the average flow velocity to the maximum flow velocity of the fluid in the tube is equal to.

Abstract Hello, the application is mainly handling, because laminar flow and turbulent flow have different mechanical characteristics. Turbulent flow not only has viscous shear stress, but also has additional shear stress (or inertial shear stress) caused by the turbulent flow of fluid points. Laminar flow, on the other hand, has only viscous shear stress. Therefore, turbulent flow has a stronger carrying capacity than laminar flow.

In addition, turbulence also has a vortex lifting effect, which is the main factor that makes the sediment suspend and transport.

Application of laminar and turbulent flow phenomena in life.

Hello, the application is mainly handling, because laminar flow and turbulent flow have different mechanical characteristics. Turbulent flow not only has viscous shear stress, but also has additional shear stress (or inertial shear stress) caused by the turbulent flow of fluid points. Laminar flow, on the other hand, has only viscous shear stress. Therefore, turbulent flow has a stronger carrying capacity than laminar flow.

In addition, turbulence also has a vortex lifting effect, which is the main factor that makes the sediment suspend and transport.

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That is, is there an example of laminar flow or turbulence in our life?

Yes, this is the formation of the boundary layer1, when the fluid begins to contact with the large plate, due to the molecular force between the fluid molecules and the solid surface (assuming that it is adsorbed on a layer), the thin layer on the solid surface of the plate does not slip off from the solid surface, and the velocity is zero;

If you don't understand it, you can't just give two specific examples, phenomena in life.

When the fluid is more viscous, the laminar flow phenomenon will be more obvious, for example, when we are stir-frying and pouring oil, the movement state of the edible oil is the laminar flow phenomenon.

This is the case.

What about the turbulence phenomenon.

What about the turbulence phenomenon.

The turbulent phenomenon of water movement, the flow characteristics of turbulent flow: when the fluid flows, there is a strong mixture between the liquid particles, and each particle point presents a chaotic and disordered state, and the movement trajectory is irregular.

Okay thank you.

Turbulent flow refers to turbulent flow, which is different from laminar flow as follows

First, the concept is different.

1. Turbulence: The fluid moves irregularly, and there is a partial velocity perpendicular to the axis of the flow tube.

2. Laminar flow: the flow rate is very small, and the fluids flow in layers and do not mix with each other.

Second, the characteristics are different.

1. Turbulence: the fluid particles are mixed with each other, the movement is disordered, and the movement elements are random.

2. Laminar flow: the flow velocity is the largest at the center of the pipe and the smallest near the wall.

3. The Reynolds number is different.

1. Turbulence: pipeline Reynolds number re>4000.

2. Laminar flow: pipeline Reynolds number re<2100.

There are two types of flow states: laminar and turbulent.

Laminar flow is the layered flow of each fluid micromass parallel to each other, without interfering with each other.

Turbulence is a strong mixing and doping between the micro-masses of various fluids, which not only moves along the direction of the main stream, but also moves perpendicular to the direction of the main stream.

Since you don't want formulas, let's just give the conclusion :

Laminar flow. The loss along the way is proportional to the 1st power of the flow velocity;

Turbulent smooth zone: the loss along the route is proportional to the power of the average flow velocity of the section;

turbulent rough zone; The loss along the course is proportional to the 2nd power of the average flow velocity of the section. (Therefore, it is also called the resistance square area).

If you have any questions, please refer to the Higher Education Edition of Fluid Mechanics

Because the critical flow velocity is related to the viscosity of the fluid, the density of the fluid and the pipe diameter (when it is a round pipe flow) or the hydraulic radius (when it is an open channel flow), and the critical Reynolds number is a proportional constant, which is very convenient to apply for a round pipe flow of 2300 (2000) and an open channel flow of 575 (500).

Single-phase flow can be further divided into incompressible fluids (liquids) and compressible fluids (gases).

Single-phase fluids obey the law of conservation of mechanical energy as they flow in the open channel of pipes.

Matter is generally divided into three states, namely solid, liquid, and gaseous. Single-phase flow is called single-phase flow if there is only one of the three phases in a tube or device.

The phase meaning of multiphase flow in fluent is richer. To quote Chapter 6 of the Introduction and Advanced Tutorial of Fluent (Beijing Institute of Technology Press): "In multiphase flow, the so-called phase can be defined as a ...... of matter with the same classFor example, particles of solid matter of the same material with different sizes can also be treated as different phases, because the ensemble of particles of the same size has a similar dynamic response to the flow field.

The above content reference: Encyclopedia - Single-phase flow

There are two main forms of fluid flow in nature, namely laminar and turbulence (which is the turbulence in the problem).Laminar flow refers to the fact that the two layers of the fluid do not mix with each other during the flow process, while turbulent flow means that the fluid is not in a stratified flow state. For the flow in the round tube, the Reynolds number is less than or equal to 2300, the pipe flow must be laminar, the Reynolds number is greater than or equal to 8000 to 12000, the pipe flow must be turbulent, and when the Reynolds number is greater than 2300 and less than 8000, the flow is in the transition zone between laminar flow and turbulent flow.

For general flows, the hydraulic radius can be used instead of the pipe diameter when calculating the Reynolds number.

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Laminar flow is the layered flow of each fluid micromass parallel to each other, without interfering with each other. Turbulence is a strong mixing and doping between the micro-masses of various fluids, which not only moves along the direction of the main stream, but also moves perpendicular to the direction of the main stream.