1. What is Prandtl Number?

Prandtl Number or Prandtl group is a dimensionless number, named after the German physicist Ludwig Prandtl, defined as the ratio of momentum diffusivity to thermal diffusivity.

2. How Does the Calculator Work?

The calculator uses the Prandtl Number formula:

Where:

• \( Pr \) — Prandtl Number (dimensionless)
• \( Gr \) — Graetz Number (dimensionless)
• \( L \) — Length (meters)
• \( Re \) — Reynolds Number (dimensionless)
• \( D \) — Diameter (meters)

Explanation: This formula calculates the Prandtl Number using Graetz Number, Length, Reynolds Number, and Diameter values.

3. Importance of Prandtl Number

Details: Prandtl Number is crucial in heat transfer calculations as it relates the relative thickness of the velocity boundary layer to the thermal boundary layer. It helps determine the rate of heat transfer in fluid flow systems.

4. Using the Calculator

Tips: Enter Graetz Number, Length in meters, Reynolds Number, and Diameter in meters. All values must be positive numbers greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical range for Prandtl Number?
A: Prandtl Number ranges from about 0.7 for gases to over 100,000 for viscous oils. Water at room temperature has a Prandtl Number of approximately 7.

Q2: How does Prandtl Number affect heat transfer?
A: Lower Prandtl numbers indicate that heat diffuses quickly compared to momentum, while higher numbers indicate the opposite.

Q3: What is the Graetz Number used for?
A: Graetz number is used in determining the thermally developing flow entrance length in ducts and heat transfer calculations.

Q4: Are there limitations to this calculation?
A: This calculation assumes constant fluid properties and fully developed flow conditions. Real-world applications may require adjustments.

Q5: When is this formula most applicable?
A: This formula is particularly useful in internal flow heat transfer problems and thermal entrance region calculations.