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Non-conservation of mass
Posted Apr 19, 2012, 3:33 p.m. EDT Mesh, Modeling Tools & Definitions, Parameters, Variables, & Functions, Results & Visualization, Studies & Solvers Version 4.2a 1 Reply
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I solved for the laminar flow equation for a eprforated pipe. I set up the boundary conditions such as I defined the inlet and outlet flow rates and set a pressure at the holes. Upon evaluation of the flow rate (surface integral of velocity), the mass does not seem to be conserved (ie: total for the holes does not equal in-out). The laminar flow equation was set to incompressible.
Could this be a factor of mesh quality?
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Do you integrate the velocity magnitude (U) on the boundaries? Because, for example in 2D, U = sqrt(u^2+v^2), i.e., all velocity components end up positive, therefore giving an incoherent mass balance. You should integrate u, v and w along the boundaries to verify mass balance.