Abstract We show that the Benjamin–Bona–Mahony (BBM) equation admits stable travelling wave solutions representing a sharp transition from constant state to periodic train. The is determined by parameters of train: length, amplitude and phase velocity, satisfies both generalized Rankine–Hugoniot conditions for exact BBM its averaged counterpart. Such shock-like structures exist if velocity trai...

In this study, a white light particle image velocimetry (WL PIV) system which employs a light sheet generated with a flash was used. The system was developed in order to provide a cost-efficient and safe alternative to laser systems while keeping the accuracy limits required for hydraulic model tests. To investigate the accuracy of WL PIV method under different flow conditions, experiments were...

A method for the simultaneous measurement of velocity and passive scalar concentration fields by means of particle image velocimetry (PIV) and planar laser induced florescence (PLIF) techniques is described here. An application of the combined PIV-PLIF system is demonstrated by performing simultaneous velocity and concentration measurements in the near field of a turbulent jet mixing flow. The ...

Velocity measurements of wind blowing near the North Sea border of Northern Germany and velocity measurements under local isotropic conditions of a turbulent wake behind a cylinder are compared. It is shown that wind gusts – measured by means of velocity increments – do show similar statistics to the laboratory data, if they are conditioned on an averaged wind speed value. Clear differences bet...

The author shows that a systematic application of thickness-weighted averaging to the Boussinesq equations of motion results in averaged equations of motion written entirely in terms of the thickness-weighted velocity; that is, the unweighted average velocity and the eddy-induced velocity do not appear in the averaged equations of motion. This thickness-weighted average (TWA) formulation is ide...

Data are presented from transcranial insonation of the middle cerebral artery (MCA) performed at intervals in 23 unconscious children for whom the outcome was subsequently poor. Once an MCA signal had been observed over a 30 minute period with time averaged velocity less than 10 cm s-1 and/or a direction of flow index, DFI, defined as 1 minus the ratio of reverse to forward flow of less than 0....

In this chapter, we present and discuss time-averaged turbulence parameters based on time and Fourier-domain analyses. In particular, we stress how the different configurations influence such parameters. All data analyzed in this chapter are obtained from velocity records sampled at a frequency of 4000Hz over a period of 180 seconds. The velocity measurements were taken at the height of 7.92cm,...

We study dynamics of freely cooling granular gases in two dimensions using large-scale molecular dynamics simulations. We find that for dilute systems the typical kinetic energy decays algebraically with time, E(t) approximately t(-1), and velocity statistics are characterized by a universal Gaussian distribution in the long time limit. We show that in the late clustering regime particles move ...