NU_HORZ_LAM_BAEHR

This function computes the laminar flat-plate Nusselt number using the Baehr formulation for isothermal surfaces. The correlation applies Reynolds and bulk-property Prandtl numbers and switches coefficients across Prandtl regimes.

A commonly used regime form is:

Nu_L = 0.664Re_L^{1/2}Pr^{1/3}

Excel Usage

=NU_HORZ_LAM_BAEHR(Re, Pr)

Re (float, required): Reynolds number with respect to plate length (-).
Pr (float, required): Prandtl number at bulk temperature (-).

Returns (float): Nusselt number with respect to plate length (-).

Example 1: Baehr example case

Inputs:

Re	Pr
100000	0.7

Excel formula:

=NU_HORZ_LAM_BAEHR(100000, 0.7)

Expected output:

186.438

Example 2: Baehr at low Prandtl

Inputs:

Re	Pr
50000	0.02

Excel formula:

=NU_HORZ_LAM_BAEHR(50000, 0.02)

Expected output:

31.6228

Example 3: Baehr at mid Prandtl

Inputs:

Re	Pr
80000	0.8

Excel formula:

=NU_HORZ_LAM_BAEHR(80000, 0.8)

Expected output:

174.345

Example 4: Baehr at high Prandtl

Inputs:

Re	Pr
120000	15

Excel formula:

=NU_HORZ_LAM_BAEHR(120000, 15)

Expected output:

579.23

Python Code

Show Code

from ht.conv_external import Nu_horizontal_plate_laminar_Baehr as ht_Nu_horizontal_plate_laminar_Baehr

def Nu_horz_lam_Baehr(Re, Pr):
    """
    Calculate the Nusselt number for laminar flow across an isothermal flat plate using the Baehr correlation.

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

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

    Args:
        Re (float): Reynolds number with respect to plate length (-).
        Pr (float): Prandtl number at bulk temperature (-).

    Returns:
        float: Nusselt number with respect to plate length (-).
    """
    try:
        return ht_Nu_horizontal_plate_laminar_Baehr(Re=Re, Pr=Pr)
    except Exception as e:
        return f"Error: {str(e)}"

Online Calculator

Re *

Reynolds number with respect to plate length (-).

Pr *

Prandtl number at bulk temperature (-).