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The Reynolds decomposition is used to derive a new set of mean-flow equations for linear viscous fluids, with low compressibility (fluids in the liquid state). Additional shear and normal stresses are related to the velocity turbulent fluctuations in order to interpret the considerable energy dissipation in processes which are accompanied by rapid changes in liquid density, at least within the frame of the local thermodynamic equilibrium (LTE) approximation. A constitutive equation for the normal turbulent stresses, which involves the turbulent bulk viscosity, is given. A closure equation for the turbulent bulk viscosity is suggested. In the field of hydraulic engineering, the model is applied to investigate the classical problem of 1D finite amplitude pressure waves propagation in liquid-filled pipes (water hammer phenomenon). Available experimental pressure data are used to calibrate the model parameters and to demonstrate the capability of the proposed theoretical model in reproducing the experimental trials. The model results are discussed with attention paid to the role played by the turbulent bulk viscosity on the energy dissipation processes. [ABSTRACT FROM AUTHOR]

This note concerns the open channel flow problem. The flow is assumed to be steady (with constant discharge), two-dimensional (with non-hydrostatic pressure distribution), without both wave breaking and sediment transport. The flow problem consists in finding the location of the free surface, and the velocity and pressure fields. The problem solution is obtained by a hybrid model which incorporates the dissipation in potential flows. In order to set up the model, this note proposes a new Picard iteration for the potential velocity field. By coupling approximate expressions for the velocity field to dynamic equations, the flow problem is reduced to one of solving a nonlinear ordinary differential equation. To illustrate the model validation, numerical simulations are performed for open channel flow over curved bottom, and the free overfall problem. In terms of free surface location and bottom pressure profile, the obtained results are in good agreement with data in literature. [ABSTRACT FROM AUTHOR]

Abstract: The work proposes an indirect turbulence model to represent the mean streamwise velocity profile of fully-developed turbulent channel flows near smooth walls. The proposed turbulence model highlights that the parameters of the velocity distribution are functions of the friction Reynolds number. It is also shown that the proposed expression for the velocity distribution is in line with the principles of dimensional analysis; it allows one to satisfy the imposed boundary conditions; in the regions close to the wall it allows to reproduce (with good agreement) the velocity profiles available in literature obtained through a Direct Numerical Simulation (DNS). [Copyright &y& Elsevier]

The article focuses on a study on non-hydrostatic pressure and the non-uniform velocity effects using different coefficients of the kinetic energy, momentum and piezometric head. It notes on the justification on the difference in energy and momentum principles in hydraulics but they believe that such explanation is not acceptable. It states that the authors' flow process has one-dimensional character.

The main aim of the present work is to provide an experimental and numerical seabed pressure dataset beneath rubble mound breakwaters with submerged berms. The estimation of the seabed pressure variation under a breakwater with a berm, useful for designing such a kind of marine structure, needs to take into account the interaction of the structure with the waves and the soil. A parametric experimental study has been carried out by varying the berm configuration, the offshore wave conditions and the water depth at the toe of the breakwater, keeping constant the values of the porosity of the berm, the armor layer and the core. From the experimental findings, the role of submerged berms in attenuating the seabed pressure under porous structures has been identified. Then, the experimental data have been used to assess the reliability of a Computational Fluid Dynamics (CFD) based numerical model. Once validated, the numerical model has been used to extend the experimental dataset by performing a parametric numerical study. New empirical formulations, aiming to predict the seabed pressure under breakwaters with a berm, have been eventually proposed. • The role of berms on the seabed pressure beneath coastal structures has been examined. • Experimental and numerical investigations have been carried out. • New formulation for seabed pressure estimation under coastal structures are proposed. [ABSTRACT FROM AUTHOR]