Detection of bubble movements via wave phase conjugation

Abstract

Wave Phase Conjugation (WPC) means reversing the propagation of waves so that initial spatial distributions of amplitudes and phases are conserved. One of the methods to conjugate ultrasonic waves is to modulate the speed of sound in a solid conjugator by an alternating electromagnetic field. The detection of bubble motions in a fluid to be considered in this work is among potentially interesting and omnipresent WPC applications in industry. As the ultrasonic waves have short wavelengths, high-order in space and time numerical methods are required for modeling. In this work, a modified version of the Nodal Discontinuous Galerkin method, which is based on the non-collocated solution and flux bases, is implemented for wave propagation in solids and liquids (for both linear and non-linear flow regimes) in an axisymmetric geometry. Being assured of the accuracy and performance of the numerical technique by evaluating some representative test cases, the detection of bubble motion and growth in a flow field using WPC is simulated with the inclusion of all elements of the WPC process: the transducer, the conjugator, and the bubbly liquid itself. The developed methodology and results can be used to design and improve measurement devices based on the WPC phenomenon.