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Eddy Viscosity Turbulence Model for Incompressible Fluid Flow in Closed Conduits

Author(s): Prashanth Reddy Hanmaiahgari; Soumen Maji

Linked Author(s): SOUMEN MAJI

Keywords: Unsteady friction; RANS equations; Turbulence; Eddy viscosity; Closed conduit flow

Abstract: Several methods have been proposed to account for unsteady friction effects during pressure surge oscillations. Convolution integral methods are an alternative within the one-dimensional models category for laminar flows. These methods use the past local accelerations and weighting functions in which computations are time consuming and require large computer memory. The convolution integral method was extended to turbulent flow for smooth and for rough pipes. These solutions provide acceptable approximations at the expense of numerical accuracy due to the approximation of the convolution integral by a limited number of weighted coefficients. The above mentioned one-dimensional unsteady friction models have been tested only for a very narrow set of unsteady flow conditions and the present state of knowledge does not guarantee their performance in general transient flow situations. The assumptions in which these models are based are likely to fail in many practical applications. In this research, equations of continuity and motion with quasi two-dimensional eddy viscosity turbulence closure model is applied to an elastic circular pipe. Since the flow is axisymmetric, the momentum and continuity equations are solved in cylindrical coordinates. The effect of roughness is included in the form of Reynolds stresses in the momentum equation and model is tested for a rapid valve closure data at different Reynolds numbers available in the literature. The pressure damping produced by the proposed model is quite accurate.


Year: 2014

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