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Mass conservation

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have a 2D fluid flow model with a flow through porous media. There is one inlet with 20 mm/s inlet velocity and I assume conservation of mass.
I want to check that the numerical mass balance of the models close with a reasonable error. To estimate if the result is reliable and not create or destroy water numerically in the calculation process.
Considering what the blog says in www.comsol.com/blogs/how-to-calculate-mass-conservation-and-energy-balance/. I went to Results > Derived Values > Integration > Line Integration
The expression you use is written as: spf.rho*(vi).

Where spf.rho is the density of the fluid and vi is the velocity.

Can someone confirm that this is the correct way to calculate mass conservation in 2D models?

2 Replies Last Post 2017年5月15日 GMT-4 17:03

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Posted: 7 years ago 2017年5月10日 GMT-4 03:24
Hi

Seems correct of vi is the flux velocity NORMAL to the outlet.

Lasse
Hi Seems correct of vi is the flux velocity NORMAL to the outlet. Lasse

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Posted: 7 years ago 2017年5月15日 GMT-4 17:03
Hi Lasse,

I'm not a comsol user and I'm following the steps to calculate mass Conservation and Energy Balance, (www.comsol.com/blogs/how-to-calculate-mass-conservation-and-energy-balance/?rnd=0.9605255224029794). I did not understand how they got the mass balance results for the transient analysis, You could share the expression of mass balance used

Best,

Katherine
Hi Lasse, I'm not a comsol user and I'm following the steps to calculate mass Conservation and Energy Balance, (https://www.comsol.com/blogs/how-to-calculate-mass-conservation-and-energy-balance/?rnd=0.9605255224029794). I did not understand how they got the mass balance results for the transient analysis, You could share the expression of mass balance used Best, Katherine

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