Modification of k-e-v 2 Turbulence Model for Turbulent Accelerated Flows in Pipes

In this study k-e-v2 turbulence model has been considered and modified for pipe flows in accelerating condition. In order to determine the characteristics of the fluid under the non-periodic accelerating conditions and using water as the working fluid, k-e-v2 model has been under taken. This model imposes the wall effects into the flow field properly. However, most of turbulence models cannot predict this phenomenon appropriately for unsteady flows. Although, k-e-v2 model is the best among the same turbulence models, however, still it needs some modifications. First, the weight coefficient of various parameters effects available in this model have been considered thoroughly. Then the most effective parameter has been obtained. It has been found that the parameter and its differential equation must be modified to correlate the experimental data desirably. Considering the point that v2 has the same dimension of k-equation, its effect is imposed into this equation. Further, this modification has been examined for internal pipe flows with different periods of accelerations. It was found that the results of some characteristics of flow such as turbulence kinetic energy and wall shear stress for different accelerations of flow are improved desirably compared to the experimental data.