Some years ago a theory was published describing compilation of digital logic system build descriptions (list of behaviors for elementary components and connections between them) into recursively computable system behavior descriptions. The current work describes an analogous theory for computer programs.

Motion-dependent fluid forces acting on a tube row with a pitch-to-diameter ratio of 1.35 are measured for several flow velocities and a series of oscillation frequencies. Fluid-damping and fluid-stiffness coefficients are obtained from motion-dependent fluid forces as a function of reduced flow velocity. Fluid-force coefficients agree reasonably with published data. Based on the fluid-force coefficients, the critical flow velocity and instability characteristics of tube arrays in crossflow can be predicted.