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October 13, 2016, 08:53 |
Reversed flow where it shouldn't
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Join Date: Jun 2016
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Hey guys,
I'm stuck with my simulation and need some help. I want to simulate flow through a manifold, to get a qualitative result of what the flow might look like. The manifold is part of a measurement system and i can briefly explain what the flow should look like in there. We have the main-flow from inlet 1 to outlet 2 due to a delta p which I dont know exactly, I just now that this flow is around 1,5 l/min. Outlet 5 is the flow to the detector, which is held constant at 120ml/min by a pump and a mfc outside of the fluid domain. Now the middle one of the three inlets shown in the picture is a special one and actually the one I'm interested in. This inlet is 0,75mm ID pipe and it has a 0,375mm OD/0,03mm ID capillary in it. The outer pipe is an outlet (pump and critical orifice outside flow domain) with around 10ml/min flow and the capillary is an inlet with 0,2ml/min flow. This results in the fact, that the fluid going in through the capillary gets immediately sucked away by the outlet 7, which is intendet. The fluid through inlet 6 is NO2, whereas the fluid through all the other inlets air is. After this simulation I want to see how deep does the NO2 get pushed in the manifold (y-direction) before it gets sucked away by outlet 7. I assumed I can use the species transport model with an inert-mixture (because there is no chemical reaction between NO2 and air) to get to this result. Now my problem is: when I set outlet 7 as pressure-outlet with target mass flow I get reversed flow in this surface. How do I get rid of this? Some information on my setting: Code:
- k-omega with low-Re correction - species-transport, inert-mixture (o2, no2, h2, air) - Minimum Orthogonal Quality = 2.61884e-02 - Maximum Ortho Skew = 8.69166e-01 - Maximum Aspect Ratio = 6.66352e+01 - operating pressure = 25000 Pa # type value 1 pressure-inlet 300 Pa / air 2 pressure-outlet 0 Pa / target mass flow=7,426e-6 kg/s 3 massflow-inlet 0 kg/s (not used in this case) / o2 4 massflow-inlet 6,8926e-11 kg/s / h2 5 pressure-outlet 0 Pa / target mass flow=5,9408e-7 kg/s 6 massflow-inlet 9,9034e-10 kg/s / no2 7 pressure-outlet 0 Pa / target mass flow=4,9507e-8 kg/s |
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