Internal waves in an unbounded non-Boussinesq flow

Weakly nonlinear internal waves in an unbounded non-Boussinesq flow with uniform stratification are treated with a Laurent-type expansion. The expansion eliminates the problem encountered with a traditional expansion in wave amplitude where higher harmonics grow exponentially faster with higher order. The results show that the second-order wave correction to the linear estimate of the wave speed of internal waves in an unbounded layer is always negative, meaning that higher amplitude waves travel slower. (C) 2011 Elsevier Ltd. All rights reserved.