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In the work presented in this Note, an Indirect Turbulence Model (ITM) is proposed to derive the mean velocity profiles in wall-bounded flows in hydraulically smooth channels having a very wide rectangular cross section. The analytical expression of the mean velocity distribution is given. The connection between the velocity distribution parameters and Reynoldsʼ number is indicated. The thickness of the viscous sublayer is evaluated. The skin friction coefficient is computed, and the analytical expression of the turbulent viscosity coefficient is provided. The validity of the proposed model is verified with reference to the velocity distributions, available in the literature, obtained with Direct Numerical Simulation (DNS) of Navier–Stokesʼ equations.

In this paper, the analysis of speed profiles in pressure pipes, which is a fluodynamic problem that is still a matter of discussion, particularly for variable flow conditions, is presented. Even if the increasing performance of PCs allows the successful adoption of numerical techniques in the simulation of practically all systems, the actually available mathematical models can supply only approximate solutions in simulating the interaction of a real viscous fluid with a surface during a turbulent flow regime. To solve this problem, a theoretically more accurate method based on dissimilar similitude has been investigated, because of its cost-effective advantage over any other comparable experimental method. More specifically, the fluodynamic analysis was carried out by applying the analogies between the fluid speed profiles in a pressure pipe and the voltage profiles on an electrolytic tank. In the paper, the theoretical backgrounds regarding the idea are reviewed, and an experimental system based on an electrolytic tank is proposed. Furthermore, the performance of the implemented system, which has been evaluated by an experimental characterization, is discussed.

By S.K. BOSE and S. DEY, Journal of Hydraulic Research Vol. 48, No. 3 (2010), pp. 388–394 The authors obtained probability density functions (PDFs) of two-dimensional turbulent velocity fluctuation...

By H.F. DUAN, M. GHIDAOUI, P.J. LEE and Y.K. TUNG, Journal of Hydraulic Research Vol. 48, No. 3 (2010), pp 354-362 In the authors' opinion, the current waterhammer models coupled with friction mode...

The direct nonlinear problem of a fluid distribution network in unsteady state of flow is dealt within this paper Referring to a class of nonlinear flow equations several issues related to the mathematical well-posedness are analyzed. A mixed variational formulation in terms of the state variables of the network along with a weak formulation with respect to the time variable is associated to the classical differential algebraic problem formulation. The strict convexity of network functional and the uniform monotonicity of the operator resulting from the temporal discretization allow the proof of the uniqueness of the solution and provide a necessary condition for global stability.