trying to simulate solid granular flow in screw conveyor (transient simulation), in solver manager when i plot the monitor for mass flow at inlet and outlet, it shows a constant line or value at inlet while at outlet
1: the values are negative
2: if we suppose that negative is just due to the fact that fluid is leaving the domain then problem is that its much larger than the inlet.
for screw to rotate i am using immersed body method.
It might be because of the mathematical model used for simulating the multiphase flow is not sufficient. Do you know what type of mathematical model is used in the software? The mathematical model might work just fine for particular cases because it has been validated using data from similar experiments. The model for example might fail to take into account the gravitational settling that happens in a screw conveyor.
One of the reason might be the gravitational effect is switched off in your simulation. if yes use -9.81 in Y axis parameter
You have a constant line at the inlet because the MFR/velocity BC is set as constant. At the outlet, if a velocity is specified as condition, CFX allows both inflow and outflow (and therefore negative MFR), and artificial walls are not erected when the specified velocity is into the domain. If a pressure/MFR condition is specified at outlet, CFX solver enforces outflow by erecting artificial walls on those faces where the flow attempts to enter the domain, so negative MFR should not occur.
If your outlet is placed in a region where inflow is expected, you can use opening BC instead of outlet, since this BC allows recirculation.
However, it is always good to set the outlet BC in a region where the flow does not exhibit recirculation (inflow in the domain).
Further, it is common practice to specify BC as MFR/velocity condition at inlet and pressure at outlet. Using only MFR/velocity conditions at both sides, inlet and outlet, is not a robust approach, since the pressure level is not specified.
- Badges
- Science topic