Effect of Shear on Ultrasonic Flow Measurement Using Nonaxisymmetric Wave Modes

Nonaxisymmetric wave propagation in an inviscid fluid with a pipeline shear flow is investigated. Mathematical equation is deduced from the conservations of mass and momentum, leading to a second-order differential equation in terms of the acoustic pressure. Meanwhile a general boundary condition is formulated to cover different types of wall configurations. A semianalytical method based on the Fourier-Bessel theory is provided to transform the differential equation to algebraic equations. Numerical analysis of phase velocity and wave attenuation in water is addressed in the laminar and turbulent flow. Meanwhile comparison among different kinds of boundary condition is given. In the end, the measurement performance of an ultrasonic flow meter is demonstrated.

BENCHMARK SOLUTIONS FOR 3-D SCATTERING FROM CYLINDRICAL INCLUSIONS

The solutions for two-dimensional diffracting objects with simple geometry such as a cylindrical inclusion are frequently used as benchmark solutions to test the accuracy of numerical schemes, such as the Finite Elements Method and the Boundary Elements Method, and to better understand the wave propagation around inclusions. The importance of having benchmark solutions available is greater in the case of the evaluation of three-dimensional scattered fields, given its increase in complexity. In this work, analytical-numerical solutions are used to evaluate the three-dimensional wave field elicited by monopole sources in the vicinity of a fluid-filled cylindrical cavity drilled through an unbounded homogeneous elastic medium. This model is used to assess the effects of the position of the source and receiver, on the propagation of both axisymmetric and nonaxisymmetric wave modes. Both frequency versus axial-wave number responses and time-domain transients are presented.