Lockhart–Martinelli parameter
# Lockhart–Martinelli parameter

The Lockhart–Martinelli parameter ($\chi$) is a dimensionless number used in internal two-phase flow calculations. It expresses the liquid fraction of a flowing fluid. Its main application is in two-phase pressure drop and boiling/condensing heat transfer calculations.

It is defined as:

    $\chi ={\frac {m_{\ell }}{m_{g}}}{\sqrt {\frac {\rho _{g}}{\rho _{\ell }}}},$

where

* $m_{\ell }$ is the liquid phase mass flowrate;
* $m_{g}$ is the gas phase mass flowrate;
* $\rho _{g}$ is the gas density;
* $\rho _{\ell }$ is the liquid density.
