Josette Bellan (née Rosentweig) is a Romanian-French-American aerospace engineer and fluid dynamicist known for her research on turbulence in high-pressure reactions, and on the interactions between fluid dynamics and thermodynamics in these reactions. She is a senior research scientist at the Jet Propulsion Laboratory (JPL) and visiting associate in the Department of Mechanical and Civil Engineering of the California Institute of Technology (Caltech).[1][2]