How to specify concentration by percentage in a mixture of gas (ch4 and Air)

  • Last Post 15 March 2019
Abhi1311 posted this 14 March 2019

Hello! I am trying to mix 2 gas which are ch4 and air to simulate a gas flow through a chamber containing one inlet and one outlet. For my simulation i need my mixed gas with a concentration like 80%ch4 and 20%air. How can i create my material like that as well as what steps i need to follow or options i need to select to complete my simulation. Also it would be helpful how should i specify my boundary condition?

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rwoolhou posted this 14 March 2019

On the inlet set the volume fraction to be 20% air and assuming you set up the species model correctly the remainder will be methane. That's an odd mixture, what are you trying to model?

Abhi1311 posted this 15 March 2019

Thank you for your reply! I think i got it. About your question I'm trying to simulate how a volatile gas like methane will perform in full concentration and when it is diluted like with 20% air, 40% air and so on till methane percentage is in single digits

rwoolhou posted this 15 March 2019

Perform as in burn, or flow? If it's the latter you don't need the species model if it's already mixed, you just need to alter the material properties to reflect those of the mixture. 

Abhi1311 posted this 15 March 2019

Perform as in flow. The step where you mentioned to alter the properties i understood but will i be able to select and specify concentration if i don't select species transport as on the material properties dialogue box i am not able to select concentration.

rwoolhou posted this 15 March 2019

No, but if you don't need to solve for species there's no benefit to including the additional equations in the solve. It'll be more (cpu) efficient to calculate the mixture properties manually and then compare the results of the single species model.