An improved k−ε turbulence model applied to incompressible round jets

The use of default coefficient values in Reynolds-averaged Navier–Stokes turbulence models often yields incorrect results because these coefficients are based on a limited flow types. To solve this problem, a method of calibration and selection of turbulence model input coefficients is proposed using the case of incompressible round jet flow in the range of Reynolds numbers from 5100 to 86 000. For the first time for round jets, the turbulence model is calibrated based on centerline velocity using all input constants. The influence of the coefficients on the axial jet velocity is analyzed. The optimal k−ε turbulence model coefficients are determined for a set of different Reynolds numbers so that the computational result matches the experimental data. Based on these data, the dependencies of the turbulence model coefficients on the Reynolds number are constructed. As a result, an improved k−ε turbulence model based on the open-source software OpenFOAM is implemented using these relations. The main advantage of the proposed model is its dependence on a single input parameter—the Reynolds number, which is based on the nozzle exit diameter. Other coefficients are determined as a function of the Reynolds number. A validation of the improved model on jet flows at other Reynolds numbers, which are not involved in the calibration process, is performed. It is found that the proposed model significantly refines the solution for incompressible jets both in the near and far field, which allows its use in other applied applications.