(fluid dynamics) The contradiction that, for incompressible and inviscid potential flow, the drag force is zero on a body moving with constant velocity relative to the fluid.

(physics) A differential operator which may be expressed as ∂_𝜇∂^𝜇=∑_(𝜇=0)³∂/∂x^𝜇∂/∂x_𝜇; it is the four-dimensional (Minkowski space) equivalent of the three-dimensional Laplace operator.

plural of d'Alembert operator

(physics) The d'Alembert operator.