I'm having issues getting COMSOL to strictly adhere to a specified inlet flow rate, and for some reason the resulting outflow from my system is also incorrect.
I'm working on a 2D axis-symmetric fluid flow model where I have an inlet/outlet and fluid passes through a porous bed on the way. I'm using Free and Porous Media Flow physics with a stationary solver, where I specify the inlet flow rate as a velocity, and the outlet as a zero pressure boundary (backflow suppressed). The problem I'm having is that my specified flow rate ~= inlet flow rate ~= outlet flow rate (according to a line integration over the inlet/outlet boundaries).
The error in the most basic geometry I set up (flow through a pipe with porous bed somewhere in the middle) gave me an error around 1%, but in the more complex system I've been developing with several inlets/outlets the problem is compounded and I end up with an outflow several orders of magnitude greater than my inflow. I've checked my math backwards and forwards and I do not believe that's the issue here. Is there a common problem with how inlet/outlet boundaries can be set up that would create this issue?
I'm working on a 2D axis-symmetric fluid flow model where I have an inlet/outlet and fluid passes through a porous bed on the way. I'm using Free and Porous Media Flow physics with a stationary solver, where I specify the inlet flow rate as a velocity, and the outlet as a zero pressure boundary (backflow suppressed). The problem I'm having is that my specified flow rate ~= inlet flow rate ~= outlet flow rate (according to a line integration over the inlet/outlet boundaries).
The error in the most basic geometry I set up (flow through a pipe with porous bed somewhere in the middle) gave me an error around 1%, but in the more complex system I've been developing with several inlets/outlets the problem is compounded and I end up with an outflow several orders of magnitude greater than my inflow. I've checked my math backwards and forwards and I do not believe that's the issue here. Is there a common problem with how inlet/outlet boundaries can be set up that would create this issue?