Contents

- 1 What does the Reynolds number tell you?
- 2 What is the Reynolds number used for?
- 3 What is a good Reynolds number?
- 4 Is a high Reynolds number good?
- 5 What is difference between laminar and turbulent flow?
- 6 What is Nusselt number formula?
- 7 Why is Reynolds number dimensionless?
- 8 What is the maximum Reynolds number?
- 9 What affects Reynolds number?
- 10 What is the value of Reynolds number for turbulent flow?
- 11 How does Reynolds number effect lift and drag?

## What does the Reynolds number tell you?

The Reynolds number, referred to as Re, is used to determine whether the fluid flow is laminar or turbulent. Technically speaking, the Reynolds number is the ratio of the inertial forces to the viscous forces. This ratio helps to categorize laminar flows from the turbulent ones.

## What is the Reynolds number used for?

The purpose of the Reynolds number is to get some sense of the relationship in fluid flow between inertial forces (that is those that keep going by Newton’s first law – an object in motion remains in motion) and viscous forces, that is those that cause the fluid to come to a stop because of the viscosity of the fluid.

## What is a good Reynolds number?

Whenever the Reynolds number is less than about 2,000, flow in a pipe is generally laminar, whereas, at values greater than 2,000, flow is usually turbulent.

## Is a high Reynolds number good?

The Reynolds number is a dimensionless number. High values of the parameter (on the order of 10 million ) indicate that viscous forces are small and the flow is essentially inviscid. Low values of the parameter (on the order of 1 hundred) indicate that viscous forces must be considered.

## What is difference between laminar and turbulent flow?

Laminar flow or streamline flow in pipes (or tubes) occurs when a fluid flows in parallel layers, with no disruption between the layers. Turbulent flow is a flow regime characterized by chaotic property changes. This includes rapid variation of pressure and flow velocity in space and time.

## What is Nusselt number formula?

the Nusselt number, which is Nu_{Dh} = 890. the hydraulic diameter of the fuel channel is: D_{h} = 13,85 mm. the thermal conductivity of reactor coolant (300°C) is: k_{H2O} = 0.545 W/m.K. the bulk temperature of reactor coolant at this axial coordinate is: T_{bulk} = 296°C. the linear heat rate of the fuel is: q_{L} = 300 W/cm (F_{Q} ≈

## Why is Reynolds number dimensionless?

In simple words, the Reynolds number is the ratio of the inertial forces acting on a fluid flowing through a closed surface such as a pipe to the viscous forces acting on it. Since, the Reynolds number is just a ratio of 2 forces, hence it is a dimensionless quantity.

## What is the maximum Reynolds number?

turbulent flow occurs over a range of Reynolds numbers from approximately 2,300 to 4,000, regardless of the nature of the fluid or the dimensions of the pipe or the average velocity. All that matters is that this specific combination of the parameters, known as the Reynolds number, fall in the range indicated.

## What affects Reynolds number?

Factors Affecting Reynolds Number Flow velocity; with an increase in flow velocity the Reynolds number increases. Characteristic Dimension; with an increase in characteristic dimension the Reynolds number increases. Fluid Density; with a decrease in fluid density the Reynolds number value decreases.

## What is the value of Reynolds number for turbulent flow?

Most of the fluid flow is turbulent. The most common example of turbulent flow is the flow of blood in arteries. The Reynold Number of turbulent flow is > 4000. ∴ For turbulent flow, the value of Reynolds number is Re > 2000.

## How does Reynolds number effect lift and drag?

The lift-to-drag ratio increases as Reynolds number increases for both the airfoils without and with GF. This drag penalty increases with Reynolds number. At higher lift coefficients, the lift-to-drag ratio increased. Hence the lift coefficient increases for a given lift-to-drag ratio.