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Mass conservation in closed fluid system
Posted 10.06.2016, 08:56 GMT-4 Fluid & Heat, Computational Fluid Dynamics (CFD), Results & Visualization Version 5.2 0 Replies
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I am using a Rotating Machinery, Laminar Flow, Frozen Rotor setup to simulate the liquid flow in a cylindrical container with a magnetic stirrer. To test the accuracy of my model I wanted to calculate the flux over different cut planes inspired by this blog: www.comsol.dk/blogs/how-to-calculate-mass-conservation-and-energy-balance/
However, even for the highest mesh preset (extremly fine) I get a flux of ~3% of the total volume per second over a cut plane perpendicular to the cylindrical axis (normal 0 0 1 => really simple surface integral over w). The fluid is incompressible water and the stirrer moves at 100 rpm which should be far from turbulent.
I consistantly get the highly inaccurate number 3% (0.3 cm^3/s out of 10 cm^3) for all resonable mesh presets which makes me suspect that I am doing something wrong?
Thanks,
Kristoffer
Hello Kristoffer Johansson
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