The Effect of Reynolds Number on Jet in Asymmetric Co-Flows: A CFD Study

1. As the jet develops, the shapes of the velocity contours are nearly elliptical and are defined as the regions half the width of the jet in this paper. In addition, they are not asymmetric

2. It is worth noting that, from previous simulations by Teng, it was found that the jet develops asymmetrically due to the geometry. As a result, half of the jet width is no longer isotropic.

3. the concentration of a species. is the fluctuating scalar field, and is the molecular diffusivity, which is not considered in this nonreactive case, since molecular diffusion has very little effect on scalar transport compared to convection. is the turbulent diffusivity, in which the viscosity of turbulent eddies is found, and is the turbulent Schmidt number. describes the relationship between the turbulent diffusivity and the molecular mass diffusivity.

4. As the continuity equation and the Navier-Stokes equations describing mass and momentum transfer are evaluated, where is the spatial coordinate, is the pressure, is the time and is the kinematic viscosity. It is the material derivative of the velocity vector.

5. The advection scheme used was of high resolution, which includes a mixing factor that combines between accurate first and second order upwind schemes, ensuring a robust solution also in regions where flow gradients change rapidly.

6. Conclusions

6.1. The k-ε model can be improved for better accuracy, but no matter how accurately it can predict the average properties of the jet development, two equation models are still not able to capture the underlying flow structures, such as vortex shedding and its effect on small- scale mixing.

6.2. For better validation and understanding of the flow field in this virtual furnace model, further measurements and advanced turbulence models or methods will be considered in future work.

7. Simulations were also carried out on the basis of data already collected, such as those used by Larsson and Teng.

8. Several materials and methods were implemented to improve this process; the geometry of the materials used and the design of the meshes were studied in order to increase the efficiency of this process.

9. Materials and Methods

10. How was it discovered?

10.1. It is nowadays well known that the initial conditions of a jet such as nozzle geometry and Re influence the development of the jet downstream. Since about four decades ago, the conclusion of a universal self-similarity behavior of all jets started to be challenged

10.2. They found that jets issuing from a smooth contraction nozzle have a larger spreading rate than jets issuing from a long straight round pipe. Moreover, the influence of the initial Re on the jet development in the selfsimilar far field depends on the type of the nozzle as well.

10.3. The centerline decay of a passive scalar will increase with higher Re if the jet issues from a smooth contraction pipe, while a jet issuing from a long straight pipe is more independent of the initial Re.