The scattering of electromagnetic waves by an obstacle is formulated as a boundary value problem analogous to the fluid dynamic problem of flows past the obstacle. The transformed Helmholtz equation in terms of Debye amplitude functions can be solved numerically in a manner similar to the solution of governing fluid flow equations. The far-field radiation condition and media interface boundary condition can also be enforced in a manner similar to the enforcement of the free-stream condition and flow-tangency condition. Various numerical methods in computational fluid dynamics CFD can be carried over for the computation of scattering characteristics. An example problem of the scattering of plane electromagnetic waves by a perfectly conducting sphere is solved in the frequency domain by a finite difference method based on the concept of generalized scattering amplitude. Numerical results are presented for ka=2.9, where k is the wave number equaling 2π divided by the wavelength and a is the radius of the sphere.