NU_CYL_CB

This function computes the average Nusselt number for forced crossflow over a single cylinder using the Churchill-Bernstein correlation. It uses Reynolds and Prandtl numbers evaluated at film temperature and provides a unified expression spanning broad laminar-to-turbulent conditions.

Nu_D = 0.3 + \frac{0.62 Re_D^{1/2} Pr^{1/3}}{\left[1 + (0.4/Pr)^{2/3}\right]^{1/4}}\left[1 + \left(\frac{Re_D}{282000}\right)^{5/8}\right]^{4/5}

Excel Usage

=NU_CYL_CB(Re, Pr)

Re (float, required): Reynolds number with respect to cylinder diameter (-).
Pr (float, required): Prandtl number at film temperature (-).

Returns (float): Nusselt number with respect to cylinder diameter (-).

Example 1: Churchill-Bernstein example case

Inputs:

Re	Pr
6071	0.7

Excel formula:

=NU_CYL_CB(6071, 0.7)

Expected output:

40.6371

Example 2: Low Reynolds number in air

Inputs:

Re	Pr
120	0.71

Excel formula:

=NU_CYL_CB(120, 0.71)

Expected output:

5.65356

Example 3: Mid Reynolds number in water

Inputs:

Re	Pr
25000	4

Excel formula:

=NU_CYL_CB(25000, 4)

Expected output:

174.054

Example 4: High Reynolds number in oil

Inputs:

Re	Pr
200000	60

Excel formula:

=NU_CYL_CB(200000, 60)

Expected output:

1727.58

Python Code

Show Code

from ht.conv_external import Nu_cylinder_Churchill_Bernstein as ht_Nu_cylinder_Churchill_Bernstein

def Nu_cyl_CB(Re, Pr):
    """
    Calculate the Nusselt number for crossflow across a single cylinder using the Churchill-Bernstein 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 cylinder diameter (-).
        Pr (float): Prandtl number at film temperature (-).

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

Online Calculator

Re *

Reynolds number with respect to cylinder diameter (-).

Pr *

Prandtl number at film temperature (-).