Nusselt number formula
======================

Nusselt number is the ratio of total heat transfer to conductive heat transfer at a
boundary in a fluid. It can be expressed using the heat transfer coefficient of the
flow, characteristic length of the system, and thermal conductivity of the fluid.

**Links:**

#. `Wikipedia <https://en.wikipedia.org/wiki/Nusselt_number#Definition>`__.

..
    TODO: rename file

.. py:currentmodule:: symplyphysics.laws.hydro.nusselt_number

.. py:data:: heat_transfer_coefficient

    :attr:`~symplyphysics.symbols.thermodynamics.heat_transfer_coefficient` of the flow.

Symbol:
    :code:`h`

Latex:
    :math:`h`

Dimension:
    :code:`power/(area*temperature)`


.. py:data:: characteristic_length

    :attr:`~symplyphysics.symbols.basic.characteristic_length` of the system.

Symbol:
    :code:`l_c`

Latex:
    :math:`l_\text{c}`

Dimension:
    :code:`length`


.. py:data:: thermal_conductivity

    :attr:`~symplyphysics.symbols.thermodynamics.thermal_conductivity` of the fluid.

Symbol:
    :code:`k`

Latex:
    :math:`k`

Dimension:
    :code:`power/(length*temperature)`


.. py:data:: nusselt_number

    :attr:`~symplyphysics.symbols.classical_mechanics.nusselt_number`.

Symbol:
    :code:`Nu`

Latex:
    :math:`\text{Nu}`

Dimension:
    :code:`dimensionless`


.. py:data:: law

    :code:`Nu = h * l_c / k`


    Latex:
        .. math::
            \text{Nu} = \frac{h l_\text{c}}{k}