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different flow rate in input and output

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Hi,

I am trying to model blood flow in the first section of the aorta when there is a ventricular assist device (VAD).
Artery model presents two inlet and four outlet:

- inlet 1 is a function variable in time, obtained by interpolation, that represents the cardiac output of 4 l/min
- inlet 2 is a constant flow of 1 l/min, that represents the outflow of the VAD, multiplied by a step function
- every outlet I have imposed a function representing a pressure variable with time

Then I use a condition of laminar inflow for the inlet and a condition of pressure without viscous stress for the outlet.
Initial conditions are zero, flow is incompressible and walls are regarded as rigid.

When I calculate the sum of the outflow is much greater than the sum of the inflow. WHY?

Thanks a lot

1 Reply Last Post 2012年7月20日 GMT-4 14:22
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 2012年7月20日 GMT-4 14:22
Hi

my reaction is too : strange, not really logical !
Flux conservation should apply, I believe; but discrepancies can also be driven by poor resolutions of gradients due to mesh density issues. Have you checked the KB knowledge base on articles about flux integrations ?

--
Good luck
Ivar
Hi my reaction is too : strange, not really logical ! Flux conservation should apply, I believe; but discrepancies can also be driven by poor resolutions of gradients due to mesh density issues. Have you checked the KB knowledge base on articles about flux integrations ? -- Good luck Ivar

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