Flow Velocity- Guranteed to be Laminar

[flash_659]

I am absolutely stumped on this last question for my assignment, I have no idea what to or how to calculate the flow from just these given constants.

Q) Water (p = 998 kg/m^3
, n = 1.0*10^-3 Pa.s at 20C) at 20C flows through a pipe of
diameter 50.0 mm. What is the maximum average flow velocity if the flow is
guaranteed to be laminar? Give your answer in mm/s.

 

[harrylin]

I am absolutely stumped on this last question for my assignment, I have no idea what to or how to calculate the flow from just these given constants.

Q) Water (p = 998 kg/m^3
, n = 1.0*10^-3 Pa.s at 20C) at 20C flows through a pipe of
diameter 50.0 mm. What is the maximum average flow velocity if the flow is
guaranteed to be laminar? Give your answer in mm/s.

Homework question?
- https://www.physicsforums.com/forumdisplay.php?f=152

 

[Enthalpy]

You have to decide a limiting Reynolds number for laminar flow and apply the formula that relates to a tube. If you've had a course this question must be pretty close to it.

 

[flash_659]

O thanks I will post in the homework section.

 

[PJC01]

I would like to clarify that laminar flow is a type of fluid flow where the fluid particles move in parallel layers with no mixing between them. This type of flow is characterized by smooth, steady, and predictable movement. In order to calculate the flow velocity, we can use the Reynolds number (Re), which is a dimensionless number that describes the ratio of inertial forces to viscous forces within a fluid.

To determine if the flow is laminar, we can use the Reynolds number formula: Re = (ρ*v*D)/μ, where ρ is the density of the fluid, v is the flow velocity, D is the pipe diameter, and μ is the dynamic viscosity of the fluid.

In this case, we are given the density (ρ = 998 kg/m^3), dynamic viscosity (μ = 1.0*10^-3 Pa.s), and pipe diameter (D = 50.0 mm = 0.05 m). We can plug these values into the Reynolds number formula and solve for the flow velocity:

Re = (ρ*v*D)/μ
Re = (998 kg/m^3 * v * 0.05 m) / (1.0*10^-3 Pa.s)
Re = 49.9*v

For laminar flow, the Reynolds number must be less than 2300. Therefore, we can set up the following inequality:
Re < 2300
49.9*v < 2300
v < 2300 / 49.9
v < 46.09

Therefore, the maximum average flow velocity for the given fluid and pipe diameter, in order to maintain laminar flow, is 46.09 mm/s. I hope this explanation helps you understand how to calculate the flow velocity in a laminar flow situation.