Investigation of k-ε Turbulent Models and Their Effects on Offset Jet Flow Simulation

Abstract

In the case in which relatively low thickness and high-velocity flow enter into the lower velocity fluid, the resulting interference field of these two flows is called the jet. This phenomenon is the dominant output of power plants and some of the dams. The jets can be divided into two categories of free jets and confined jets, caused by the distance from the discharge to limited boundaries points. The offset jet is a type of confined jet in which both free surface and wall boundaries are near the diffusion location. The jet flow due to the extreme curvature in the main flow path and the proximal portion of this flow with solid boundaries have characteristics that make it difficult to solve with simple turbulence models.In this research, the offset jet phenomenon and related issues have been investigated. For this purpose, the offset jet flow pattern and probable factors in the complexity of this model have been simulated using Fluent software which analyses fluid flow in a two dimensional and three dimensional finite volume method. The simulation of offset jet flow pattern has been performed with a focus on investigating different models of turbulence k-ε, also boundary conditions, various wall functions and other effective coefficients in the numerical model and the model results compared with test case data findings and validating results, the necessary approaches in numerical simulation of this phenomenon for using in the next stages had been taken.

Numerical Modeling of Soil Erosion with Three Wall Laws at the Soil-Water Interface

“…This amount is a result of the Integration of the erosion law along the whole length of the hole and the multiplication of the results and the initial circumference of the hole. The linear classical erosion law: ̇= ( − ) was used, with the erosion constants = 5.5 10 −4 / and τ = 7 as identified for a soil sample [10,11]. The results also indicate that the SWF (Scalable Wall Function) law is not compatible to improve the near wall calculation due to poor estimates.…”

“…Various models for the prediction of sand erosion rate have been developed [2,4], the one developed by Bonelli et al (2006Bonelli et al ( , 2008 was for interpreting the whole erosion test with a constant pressure drop [4,5]. This type of model yielded a characteristic erosion time depending on the initial hydraulic gradient and the coefficient of erosion [6][7][8][9][10][11][12]; Another area of research is piping, which involves the formation and development of a continuous pipe within an earthen structure by the erosion of surrounding soil material driven by a hydraulic gradient. Failure of this type of structure can occur in one of three modes: piping through the fill, piping from the fill to the foundation and piping through the foundation.…”

Effect of Mixed Gas Ratio on Cooling Performance of Impinging Jets

“…An overview of the analysis model is shown below. ・Unsteady analysis of incompressible fluid ・Consideration of turbulence (Realizable k- model applied) ・Standard wall function ・Consideration of gravity ・Consideration of mixed gas composition using a species transport model As the turbulence model, we selected the Realizable k- model 20,21) , which has been applied to a wide range of flows and can appropriately predict the spread angle of an axisymmetric jet. However, it should be noted that the accuracy of air entrainment has not been verified against other turbulence models, and there is room for further optimization.…”

Numerical Simulation of Hydrodynamic Properties of Alex Type Gliders

“…1 is a constant value, = and 2 a function that adopts a value equal to 1 for boundary layer flow and zero for non-shear stress. The equations used are Navier-Stokes, continuity, and turbulence models, respectively, as follows [33]:…”