Navid's scientific activities began with 1809 editing and publishing the works of Saint Gotha and revising B.F. de Belidor (1698? 176 1), which aroused his interest in the basic theory of engineering science. The traditional education of mathematical analysis and the practical experience of civil engineering in Paris Polytechnic School are beneficial to his mechanical research. Naville's main contribution is to establish the basic equations of fluid mechanics and elasticity respectively. In 182 1, he generalized L. Euler's equation of fluid motion and considered intermolecular forces, thus establishing the basic equations of fluid equilibrium and motion. The equation contains only one viscosity constant. 1845, on the basis of the continuum model, G.G. Stokes improved his equations of motion of fluid mechanics, and obtained the rectangular coordinate component form of the equations of motion of viscous fluid with two viscosity constants (hereinafter referred to as Naville-Stokes equation, that is, N-S equation). 182 1 year, Naville also derived the equilibrium equation and motion equation of elastic solid from the molecular model (published in 1827), and regarded each molecule as a force center, which only contained an elastic constant. 1823a.-L. Cauchy obtained the basic equations of isotropic elasticity with two elastic constants.

Navid's other achievements in mechanics are as follows: firstly, (1820) the fourth-order partial differential equation of simply supported rectangular plate was solved by double trigonometric series; Mechanical work is introduced into engineering to measure the efficiency of machines. In engineering, he changed the tradition of designing and building suspension bridges only by experience, and adopted theoretical calculation in the design.

Navid's scientific papers are published in various scientific journals in France, the papers on the basic equations of fluid mechanics are published in the annual chemical journal, Volume 19 (182 1), and the articles on the equilibrium of elastic solids and equations of motion are published in the research report collection of French Academy of Sciences, Volume 7 (1827).