Discussion on hydrodynamic stability

MR D. H. BRERETON, Central Electricity Research Laboratories: In Paper 14, the Authors' stability analysis is based on a single differential equation which is the equation of liquid momentum. But I believe it is true that numerical codes based only on time-dependent thermal effects will adequately represent the flow oscillations.

If, however, we do assume equation 12, the Authors say that an oscillatory mode is predicted by a first order equation and that the right-hand side constant term helps to determine stability. Could the authors clarify their work, by comparing it with a conventional analysis in terms of a linear system with a pair of complex right-hand £-plane poles?