Reynolds & Velocity: Finding Mean & Max Velocities

[Libertiene]

Hi,

I have been given a couple of questions in which i have to draw a velocity profile in a pipe etc.

We are asked to find the mean & maximum velocitys, velocity pressure & pressure drop. the only 2 parameters we are given are the RE (Reynolds number) & pipe size. We are also told that the fluid is water. So thus we know the density & dynamic viscosity.

The only way i can see that i can find the velocity would be to transpose the formula for RE to get velocity (please correct me if I am wrong). But my question is, would this be the mean or maximum velocity? I have assumed mean, but if i am wrong i have stuffed the hole thing.

Regards

 

[stewartcs]

Hi,

I have been given a couple of questions in which i have to draw a velocity profile in a pipe etc.

We are asked to find the mean & maximum velocitys, velocity pressure & pressure drop. the only 2 parameters we are given are the RE (Reynolds number) & pipe size. We are also told that the fluid is water. So thus we know the density & dynamic viscosity.

The only way i can see that i can find the velocity would be to transpose the formula for RE to get velocity (please correct me if I am wrong). But my question is, would this be the mean or maximum velocity? I have assumed mean, but if i am wrong i have stuffed the hole thing.

Regards

The velocity used in the computation of the Reynold's number is indeed the mean velocity.

CS

 

[Mene]

Dear student,

Thank you for your question. To find the mean and maximum velocities, you can use the formula for Reynolds number (RE) and solve for velocity. However, this will only give you the mean velocity. To find the maximum velocity, you will need to consider the velocity profile in the pipe. The maximum velocity will occur at the center of the pipe, while the mean velocity will be an average of the velocities across the entire cross-sectional area of the pipe.

To find the velocity pressure and pressure drop, you can use Bernoulli's equation, which relates the velocity, pressure, and elevation of a fluid in a pipe. You will need to know the velocity, pressure, and elevation at two different points along the pipe to calculate the pressure drop.

Since you are given the RE and pipe size, you can also use the Darcy-Weisbach equation to calculate the pressure drop. This equation takes into account the fluid properties, pipe size, and roughness of the pipe walls.

I hope this helps clarify your approach to solving this problem. Let me know if you have any further questions.

Best regards,