Budapest University of Technology and EconomicsFaculty of Civil Engineering - Since 1782

This research concentrates on the unsteady and turbulent phenomena of open channel flow, in particular, wave motion of such amplitude that the simple linear wave approximation of Airy, so much preferred in the usual engineering practice, is no longer appropriate. The observed phenomena include both weakly nonlinear waves (typically approximated by the Korteweg–de Vries equation or the like) and strongly nonlinear ones, like solitary waves (which have analytic theory). While the former waves often can be dealt with using perturbation techniques, the properties of the latter can only be explained with fully nonlinear models. Nonlinear waves can be generated by hydraulic structures (e.g. during flood conditions), by navigation, by the operation of hydraulic controls or by accidents.

 In actual channels wind shear and bed shear also interact with the wave field, thus the necessary approach exceeds the framework of the free surface flow model.

 Nonlinearity may result in interaction between waves and mean flow, wave instability, wave breaking (with the associated air entrainment) etc.

 Such hydrodynamic phenomena can affect the hydraulic conditions in the channel and pose engineering problems. The more violent impacts of water waves on walls create velocities and pressures having magnitudes much larger than those associated with the propagation of ordinary waves under gravity. The related unexpected erosive action (especially on dykes and other earthen structures) can warrant the reinforcement or redesign of the channel (or the operation thereof) if concentrated or enduring intensive (wave) action occurs at certain points. Another, not less interesting effect is the wave action on the bed material: dynamic sediment transport processes are generated by the dynamic action of the aforementioned flow phenomena.

 We expect that the study of these phenomena will be done by using at least two of the following three approaches: theory, experiments, numerical analysis. Experiments may include field observations. The development of a new measurement technique or numerical method is also considered as a valid scientific achievement. For the analysis of the flow fields and the wave phenomena modern mathematical tools like wavelet transformation or the Hilbert spectrum has to be also considered besides the classical Fourier transformation.