KnudsenModel: A physically consistent Python framework for computing evaporative cooling of liquid jets
Description
We present KnudsenModel, an open-source Python implementation of the Knudsen model for computing evaporative cooling of microscopic liquid jets in vacuum. The code builds on widely used scientific Python packages and provides a transparent and flexible framework that can be applied to both cylindrical jets and spherical droplets. A fixed-mass radial discretization is employed to consistently account for the coupled evolution of mass loss and density, ensuring physically accurate predictions of both temperature and jet or droplet diameter. We analyze the numerical behavior of the method, including convergence properties and comparisons with literature calculations based on alternative discretization schemes, revealing that, in particular for water droplets, the present formulation captures a shallow minimum in the diameter that reflects the interplay between evaporation-induced mass loss and water's density anomaly—a feature absent in previous results.