NU_EXT_HORZ_PLATE

This function computes the Nusselt number for external forced convection along a horizontal flat plate. It can use an explicitly selected correlation or automatically choose a laminar or turbulent method based on a transition Reynolds number.

In automatic mode, a piecewise method selection is used:

Nu = \begin{cases} f_{\text{lam}}(Re, Pr), & Re < Re_{\text{transition}} \\ f_{\text{turb}}(Re, Pr), & Re \ge Re_{\text{transition}} \end{cases}

Excel Usage

=NU_EXT_HORZ_PLATE(Re, Pr, L, x, plate_method, laminar_pref, turbulent_pref, Re_transition)

• Re (float, required): Reynolds number with respect to plate length (-).
• Pr (float, required): Prandtl number with respect to bulk properties (-).
• L (float, optional, default: null): Plate length (m).
• x (float, optional, default: null): Plate distance for local calculation (m).
• plate_method (str, optional, default: null): Correlation method name (-).
• laminar_pref (str, optional, default: “Baehr”): Preferred laminar correlation name (-).
• turbulent_pref (str, optional, default: “Schlichting”): Preferred turbulent correlation name (-).
• Re_transition (float, optional, default: 500000): Reynolds number for laminar-turbulent transition (-).

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

Example 1: Horizontal plate turbulent example

Inputs:

Re	Pr
10000000	0.7

Excel formula:

=NU_EXT_HORZ_PLATE(10000000, 0.7)

Expected output:

11497

Example 2: Horizontal plate laminar range

Inputs:

Re	Pr
80000	0.71

Excel formula:

=NU_EXT_HORZ_PLATE(80000, 0.71)

Expected output:

167.545

Example 3: Horizontal plate with explicit method

Inputs:

Re	Pr	plate_method
300000	0.9	Baehr

Excel formula:

=NU_EXT_HORZ_PLATE(300000, 0.9, "Baehr")

Expected output:

351.137

Example 4: Horizontal plate with custom transition

Inputs:

Re	Pr	Re_transition
600000	1.1	200000

Excel formula:

=NU_EXT_HORZ_PLATE(600000, 1.1, 200000)

Expected output:

1637.17

Python Code

Show Code

from ht.conv_external import Nu_external_horizontal_plate as ht_Nu_external_horizontal_plate

def Nu_ext_horz_plate(Re, Pr, L=None, x=None, plate_method=None, laminar_pref='Baehr', turbulent_pref='Schlichting', Re_transition=500000):
    """
    Calculate the Nusselt number for forced convection across a horizontal plate.

    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 with respect to bulk properties (-).
        L (float, optional): Plate length (m). Default is None.
        x (float, optional): Plate distance for local calculation (m). Default is None.
        plate_method (str, optional): Correlation method name (-). Valid options: Baehr, Churchill Ozoe, Schlichting, Kreith. Default is None.
        laminar_pref (str, optional): Preferred laminar correlation name (-). Valid options: Baehr, Churchill Ozoe. Default is 'Baehr'.
        turbulent_pref (str, optional): Preferred turbulent correlation name (-). Valid options: Schlichting, Kreith. Default is 'Schlichting'.
        Re_transition (float, optional): Reynolds number for laminar-turbulent transition (-). Default is 500000.

    Returns:
        float: Nusselt number with respect to plate length (-).
    """
    try:
        return ht_Nu_external_horizontal_plate(
            Re=Re,
            Pr=Pr,
            L=L,
            x=x,
            Method=plate_method,
            laminar_method=laminar_pref,
            turbulent_method=turbulent_pref,
            Re_transition=Re_transition,
        )
    except Exception as e:
        return f"Error: {str(e)}"

Online Calculator

Re *

Reynolds number with respect to plate length (-).

Pr *

Prandtl number with respect to bulk properties (-).

L

Plate length (m).

x

Plate distance for local calculation (m).

plate_method Optional Baehr Churchill Ozoe Schlichting Kreith

Correlation method name (-).

laminar_pref Optional Baehr Churchill Ozoe

Preferred laminar correlation name (-).

turbulent_pref Optional Schlichting Kreith

Preferred turbulent correlation name (-).

Re_transition

Reynolds number for laminar-turbulent transition (-).