A re-examination of weakly-nonlinear acoustic traveling waves in thermoviscous fluids under Rubin–Rosenau–Gottlieb theory

We revisit the analysis of acoustic traveling waves in thermoviscous fluids modeled by what has come to be known as RRG-theory. In particular, the propagation anomaly reported in Ref. Jordan et al. (2014) is resolved and conditions under which the traveling wave solutions (TWS)s presented here are physically plausible are established for gases and liquids. In addition, the analysis is extended to the case of retrograde fluids, the findings reported here are compared with those of classical acoustics theory, and we propose a new dimensionless number based on RRG-theory.