LAM_ENTRY_BAEHR

This function estimates the average laminar Nusselt number in the thermal and hydrodynamic entry region of a circular tube using the Baehr–Stephan correlation. It accounts for Reynolds number, Prandtl number, and geometry through the developing-flow length scale.

Excel Usage

=LAM_ENTRY_BAEHR(Re, Pr, L, Di)

Re (float, required): Reynolds number (-).
Pr (float, required): Prandtl number (-).
L (float, required): Pipe length (m).
Di (float, required): Pipe diameter (m).

Returns (float): Laminar entry-region Nusselt number (-).

Example 1: Baehr-Stephan example

Inputs:

Re	Pr	L	Di
100000	1.1	5	0.5

Excel formula:

=LAM_ENTRY_BAEHR(100000, 1.1, 5, 0.5)

Expected output:

72.654

Example 2: Lower Reynolds number

Inputs:

Re	Pr	L	Di
5000	7	1	0.05

Excel formula:

=LAM_ENTRY_BAEHR(5000, 7, 1, 0.05)

Expected output:

24.8796

Example 3: Mid Reynolds number

Inputs:

Re	Pr	L	Di
20000	0.9	2	0.1

Excel formula:

=LAM_ENTRY_BAEHR(20000, 0.9, 2, 0.1)

Expected output:

22.9378

Example 4: Longer pipe length

Inputs:

Re	Pr	L	Di
80000	2	3	0.2

Excel formula:

=LAM_ENTRY_BAEHR(80000, 2, 3, 0.2)

Expected output:

65.9616

Python Code

Show Code

from ht.conv_internal import laminar_entry_Baehr_Stephan as ht_laminar_entry_Baehr_Stephan

def lam_entry_baehr(Re, Pr, L, Di):
    """
    Calculate laminar entry Nusselt number using Baehr-Stephan.

    See: https://ht.readthedocs.io/en/latest/ht.conv_internal.html

    This example function is provided as-is without any representation of accuracy.

    Args:
        Re (float): Reynolds number (-).
        Pr (float): Prandtl number (-).
        L (float): Pipe length (m).
        Di (float): Pipe diameter (m).

    Returns:
        float: Laminar entry-region Nusselt number (-).
    """
    try:
        return ht_laminar_entry_Baehr_Stephan(Re=Re, Pr=Pr, L=L, Di=Di)
    except Exception as e:
        return f"Error: {str(e)}"

Online Calculator

Re *

Reynolds number (-).

Pr *

Prandtl number (-).

L *

Pipe length (m).

Di *

Pipe diameter (m).