MODULES

Isothermal Mixing Process Of Two Confined Opposing Jets In A Parallel Channel

Problem Definition:

The numerical model considered in this section is an isothermal, laminar mixing process of two confined non-reacting opposing jets in a parallel channel. The two species enter through two different equisized slots positioned exactly opposite to each other creating a counter flow when they meet each other. The fluid mixture then flows out of the channel along a direction normal to the jet axes. Figure 1.1(a) shows the entrance and exit regions of the channel. Since the geometry is symmetrical about the axes of the inlet jets, one half of the domain is chosen for the study. Figure 1.1(b) shows the numerical model of the problem of study. The widths of the two inlet slots of the channels (D) and the height (h) are equal whereas the length (L) of the computational domain is 12 times to that of the slot width. We choose Argon and air as the two gases, with the latter entering from the bottom. The left boundary represents the symmetry plane while the right boundary represents the outlet of the flow domain. The walls are impermeable. The temperatures of the two impinging jets are constant and equal such that mixing that takes place is isothermal. Fully developed velocity profiles of both the jets are specified at the entrance to the mixing region. The inlet Re and Pe are 60 and 42, respectively. For the numerical simulation uniform hexahedral cells of 24000 numbers are used.




(a)



(b)
Figure 1.1: (a)Schematic of the flow domain, (b)Computational domain of the problem


Results:

The mass fraction of Ar along a plane perpendicular to axis of the channel at an axial length of 0.4 m from the inlet are plotted and compared with the work of Gomes and Caldeira [1]. The comparison is shown in Fig. 1.2 which represents a reasonably good match with the published literature.


Figure 1.2: Validation with Gomes and Caldeira[1]: Comparison of Argon mass fraction profile along a plane perpendicular to channel axis at a distance of 0.4m from the inlet

References

[1] Gomes M.M. and Caldeira A.B. (2007) ‘Numerical study of the mixing process in laminar confined opposing jets’, 19th International Congress of Mechanical Engineering, Proceedings of COBEM, Brasilia.